A&A 368, 912-931 (2001)
DOI: 10.1051/0004-6361:20000577

Statistical analysis of intrinsic polarization, IR excess and projected rotational velocity distributions of classical Be stars[*]

R. V. Yudin1,2 [*]


1 - Central Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, 196140 Saint-Petersburg, Russia
2 - Isaac Newton Institute of Chile, St.-Petersburg Branch, Chile

Received 9 December 1999 / Accepted 22 December 2000

Abstract
We present the results of statistical analyses of a sample of 627 Be stars. The parameters of intrinsic polarization $(p_{\ast})$, projected rotational velocity $(v \sin{i})$, and near IR excesses have been investigated. The values of $p_{\ast }$ have been estimated for a much larger and more representative sample of Be stars ($\approx$490 objects) than previously. We have confirmed that most Be stars of early spectral type have statistically larger values of polarization and IR excesses in comparison with the late spectral type stars. It is found that the distributions of $\,p_{\ast}\,$ diverge considerably for the different spectral subgroups. In contrast to late spectral types (B5-B9.5), the distribution of $\,p_{\ast}\,$for B0-B2 stars does not peak at the value $p_{\ast}=0$%. Statistically significant differences in the mean projected rotational velocities ( $\overline{v\sin{i}}$) are found for different spectral subgroups of Be stars in the sense that late spectral type stars (V luminosity class) generally rotate faster than early types, in agreement with previously published results. This behaviour is, however, not obvious for the III-IV luminosity class stars. Nevertheless, the calculated values of the ratio $v_{\rm t}/v_{\rm c}$ of the true rotational velocity, $v_{\rm t}$, to the critical velocity for break-up, $v_{\rm c}$, is larger for late spectral type stars of all luminosity classes. Thus, late spectral type stars appear to rotate closer to their break-up rotational velocity. The distribution of near IR excesses for early spectral subgroups is bi-modal, the position of the second peak displaying a maximum value $E(V-L)\approx1\mbox{$\,.\!\!\!^{\rm m}$ }3$ for O-B1.5 stars, decreasing to $E(V-L)\approx0\mbox{$\,.\!\!\!^{\rm m}$ }8$ for intermediate spectral types (B3-B5). It is shown that bi-modality disappears for late spectral types (B6-B9.5). No correlations were found between $p_{\ast }$ and near IR excesses and between E(V-L) and $v\sin{i}$ for the different subgroups of Be stars. In contrast to near IR excesses, a relation between $p_{\ast }$and far IR excesses at 12 $\mu $m is clearly seen. A clear relation between $p_{\ast }$ and $v\sin{i}$(as well as between $p_{\ast }$ and $\overline{v\sin{i}}/v_{\rm c}$) is found by the fact that plots of these parameters are bounded by a "triangular" distribution of $p_{\ast }$:$v\sin{i}$, with a decrease of $p_{\ast }$towards very small and very large $v\sin{i}$ (and $\overline{v\sin{i}}/v_{\rm c}$) values. The latter behaviour can be understood in the context of a larger oblateness of circumstellar disks for the stars with a rapid rotation. From the analysis of correlations between different observational parameters we conclude that circumstellar envelopes for the majority of Be stars are optically thin disks with the range of the half-opening angle of $10\hbox{$^\circ$ }<\Theta<40\hbox{$^\circ$ }$.

Key words: classical Be stars: polarization - projected rotational velocities - near IR excesses - far IR excesses


1 Introduction

One of the challenging questions in Be stars investigations is the geometrical form of their circumstellar (CS) envelopes. There is still active debate as to the average value of the opening angle of CS disks around classical Be stars and on the application of the wind-compressed disk model (WCD). The ideas on this matter at present are rather controversial. Most authors have considered geometrically thin CS disks with half-opening angles $\Theta<3\hbox{$^\circ$ }$ as follows from the WCD theory of Bjorkman & Cassinelli (1993) and Owocki et al. (1994) (see for example Wood et al. 1997; Quirrenbach et al. 1997 etc.). However, acceptance of such a narrow disks faces several problems in the interpretation of spectroscopic characteristics (Moujtahid et al. 1999; Rivinius et al. 1999) and the observed IR excesses in Be stars (Porter 1997). Moreover, the observed phase transitions - Be $\Leftrightarrow$ Be-shell $\Leftrightarrow$ normal B - cannot be explained in the framework of a geometrically thin disk model (Moujtahid et al. 1999). Others used disk models with larger values of $\Theta\approx6\hbox{$^\circ$ }$ (Porter 1996) or $\Theta\approx13\hbox{$^\circ$ }\rightarrow15\hbox{$^\circ$ }$ (Hanuschik 1996; Waters et al. 1987) removing some of the difficulties. Finally, some authors recently returned to the model of flattened ellipsoids or spheroidal envelopes (Moujtahid et al. 1999) similar to those proposed earlier by Doazan & Thomas (1982). Although a low level of intrinsic polarization of Be stars is considered as an indication that the envelope must be strongly flattened, other geometries can produce the same level of polarization (see Wood et al. 1996a, 1996b). The IR excesses and spectroscopic characteristics, considered separately, also do not provide unique interpretation on CS geometries. Nevertheless, it is well established that the observed IR excess and polarization of radiation for classical Be stars both have a common origin. The excess is due to free-free and free-bound emission from the dense ionized CS gas, with the polarization being engendered by scattering within clouds of free electrons around the star. Moreover, classical Be stars are very fast rotators and at least a few of them rotate close to their break-up velocities. This rapid rotation is considered as a trigger mechanism for CS envelope formation. To obtain some conclusions on the geometry of CS envelopes around classical Be stars, analysis of correlations between different observational parameters seems strongly desirable (see, for example, Coté & Waters 1987). For the same reason, it is very important to investigate each of the observed parameters statistically for as large a representative sample as possible. During the last 20 years there have been several attempts to carry out such kinds of investigation for large samples of classical Be stars (from 50 up to 200 objects). However, such sample sizes are still sometimes insufficiently large to provide irrefutable conclusions and some authors indicate this fact themselves (see, for example, Quirrenbach et al. 1997 or Ghosh et al. 1999). By taking a relatively large sample of 90 objects, by adding the "new'' data from Ghosh et al. (1999) and McDavid (1999, 2000) to the "old'' data from McLean & Brown (1978) and Poeckert et al. (1979), Yudin (2000) came to quite different conclusions on the dependence between $\,p_{\ast}\,$and $\,v\sin{i}\,$ than those of McLean & Brown (1978) who used only 67 stars.

The general aim of the proposed exercises here is to investigate statistically the data of $\,p_{\ast}\,$ and $\,v\sin{i}\,$ for the largest possible sample of classical Be stars, to compare the behaviour with near and far IR excesses and to search for possible correlations between the parameters. Another aim is to investigate possible differences between spectral subgroups from the general assembly of classical Be stars. These analyses may give new insight on the configuration of CS envelopes.

2 Selection procedure

Up till now, there is no statistical information on whether or not classical Be stars can be treated as a homogeneous group. The largest database, SIMBAD, contains only 82 objects which are classified as Be stars but, at the same time, 884 objects are classified as O-B emission line stars. The largest revised catalogue of Be stars of Jaschek & Egret (1982) contains 1155 objects but a significant fraction of these belong to the young Herbig Be star group.

For the statistical analysis here, data for 627 Be stars have been compiled from different sources, taking into account an overlap of the list of emission line stars from the SIMBAD database and the catalogue of Be stars of Jaschek & Egret (1982). All Be stars which have been considered in the past as young Herbig Be stars have been excluded; a few Be stars from recent papers (see, for example, Steele et al. 1999) have been added. Of course it is impossible to be sure that all the collected objects are definitely of classical type, but the fraction of "doubtful" objects cannot be large (as follows from further discussion, see Sect. 6 and Fig. 2). Thus we can say that the compilation represents the largest ever, more or less homogeneous, sample of classical Be stars. Note that for selection, we collected only stars of III, IV and V luminosity class and the sample does not include any supergiants. Emission line stars of the spectral type A and later are also excluded. No limitation has been made on the level of observed polarization ( $p_{\rm obs}$) of the sample stars. Thus we have in hand for statistical study:

1.
    497 stars with polarization data;
2.
    246 stars with values of near IR excess E(V-L);
3.
    151 stars with values of IR excess at 12 $\mu $m, and
4.
    463 stars with $\,v\sin{i}$ values.
All collected data are presented in Appendix I. It is, of course, of direct interest to investigate the distributions of the observed parameters for the entire sample, but in addition, it is also important to compare the data according to different spectral subgroups. The latter is obviously important to astrophysical understanding but such breakdown also allows investigation of the homogeneity of the total assembly. To obtain statistically representative data sets, we separate the entire sample into four subgroups. Subdividing our list yields 174 stars in the interval O-B1.5, 170 stars in the interval B2-B2.5, 147 stars in the interval B3-B5.5, and 135 stars in the interval B6-B9.5. This separation was not justified physically a priori, but it reflects an approximately equal range of effective temperature $T_{\rm e}$( $\Delta T_{\rm e}\approx5000$ K) for the last three subgroups.

3 Data reduction

Because the main aim of the present investigation is a statistical study of different observed parameters and correlations between them, it is important to minimize any uncertainties and all kind of statistical biases. Since a principal characteristic of Be stars is their temporal variability, it is best to use the mean values of investigated parameters for each star. The averaging was done by the weighting procedure according to the standard errors of individual measurements (see, for example, Smart 1958).

For the discussion of the various parameters, it is useful to construct the relative distributions of observed values in the form of histograms. For this reason it is very important to choose the best binwidths for the distributions. As will be shown below, the chosen binwidths of 0.3%, $0\mbox{$\,.\!\!\!^{\rm m}$ }3$ and 50 kms-1 for polarization, colour and rotational velocity respectively are typically larger than the error associated with the individual measurements and even larger than the range of variability associated with any of the stars. Consider now the reduction of each of the recorded parameters.

3.1 Reduction of v sin i

At present, most Be star investigations have used the data of $\,v\sin{i}\,$ mainly from Slettebak (1982) (164 classical Be stars). Other old data are also available and these are supplemented by numerous more recent collections. The only problem in compiling $\,v\sin{i}\,$ values from different sources is that they have different scales and accurate calibrations between the compiled data are required to avoid systematic errors. It is well known that there is a difference between the "new'' and "old'' Slettebak's scales (Slettebak et al. 1975). First of all we compared the $v\sin{i}$ data of Slettebak (1975) with those determined or compiled by others for the same stars and calculated least-squares fits to the data. Following this calibration process, we transformed individual values of $\,v\sin{i}\,$ from different sources into the common "new'' scale of Slettebak et al. (1975). Stars which after transformation provided strong disparities in their values according to the source catalogue were excluded. Average weighted values of $\,v\sin{i}\,$ and associated standard errors were obtained for each star using the weighting procedure already mentioned above (see Smart 1958). For the case of single measurements, we used the value of a standard error indicated in the reference or adopted a value for the error equal to 10% of the measured value. This procedure allows exclusion of most systematic and incidental errors and helped to obtain a new expanded homogeneous data set. The determined values of $\,v\sin{i}\,$ for each star with the standard error are presented in Appendix I. It can be seen that for more than 95% program stars, the standard error is less than $\pm 40$ kms-1.

3.2 Reduction of $\mathsfsl{E(V-L)}$

The values of near IR excesses E(V-L) were calculated by a classical approach using the measurements of observed and normal colour indices and interstellar reddening in the respective photometric bands, this being summarized as:

\begin{displaymath}E(V-L)=(V-L)_{\rm obs}-(V-L)_0-(A_{V}-A_{L})
\end{displaymath} (1)

where $(V-L)_{\rm obs}$ and (V-L)0 are the observed and normal colour indices and $\,A_{V}$, $A_{L}\,$ are the values of interstellar reddening in the respective photometric bands. We assume that no circumstellar dust environment exists around most of the considered stars and E(V-L) is the excess due to the contribution of circumstellar gas. For most stars the values of $\,A_{V}$, $A_{L}\,$ were calculated assuming a normal extinction law in the form $\,A_{V}=3.1\times E(B-V)\,$, $\,A_{L}\approx0.06A_{V}\,$ and $\,E(B-V)=(B-V)_{\rm obs}-(B-V)_{0}\,$(for a detailed discussion, see, for example, Dougherty et al. 1994). In principle, this procedure may lead to the over-dereddening but the error in most cases does not exceed $\,0\mbox{$\,.\!\!\!^{\rm m}$ }2\,$and is unimportant, taking into account the chosen histogram binwidth for E(V-L) of $0\mbox{$\,.\!\!\!^{\rm m}$ }3$. The values of (V-L)0 and (B-V)0 were taken from Straizys (1977). It is easy to show that due to the uncertainty $\sigma_{E(B-V)}\approx0\mbox{$\,.\!\!\!^{\rm m}$ }05$, the uncertainty in E(V-L) is about $0\mbox{$\,.\!\!\!^{\rm m}$ }2$. Of greater importance is the study of errors due to the range of photometric variability for individual objects. Most classical Be stars are photometric variables on different time scales. Hubert & Floquet (1998) recently investigated photometric variability of a sample of 289 classical Be stars using the Hipparcos photometric data. They found that most of their program stars (about 33%) exhibited photometric variability $0\mbox{$\,.\!\!\!^{\rm m}$ }1\leq\Delta H_{\rm p}\leq0\mbox{$\,.\!\!\!^{\rm m}$ }3$. Other stars usually show a lower level of photometric variability. Similar conclusions were made recently by Moujtahid et al. (1998) who compiled the values of $\,\sigma_{V}\,$for 50 well known classical Be stars. Moreover, for the calculation of E(V-L), optical and IR data were selected to be as close as possible in time.

3.3 Reduction of $\mathsfsl p_{\ast}$

Currently, the intrinsic polarization components have been estimated for only about 90 classical Be stars.

  \begin{figure}
\par\includegraphics[width=8cm,height=6.3cm,clip]{9470f1a.ps}\par\vspace*{5mm}
\includegraphics[width=7.8cm,height=6cm,clip]{9470f1b.ps}\end{figure} Figure 1: Dependence between the interstellar polarization and the distance in the $5\hbox {$^\circ $ }$ field surrounding a few program stars. The numerical values attached to the curves refer to the position angle of interstellar polarization according to distance
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In order to obtain a $p_{\ast }$ value for each star, its interstellar component, $p_{\rm is}$, needs to be subtracted. This is best done using the "field star method" whereby the local growth of $p_{\rm is}(D)$ with distance, (D), is first obtained from measurements of stars close to the line of sight of the target star. According to the distance of the considered Be star, an estimate for its $p_{\rm is}$ component is then made from the calibration and vectorially subtracted using the component Stokes parameters. The selected fields ranged from $1\hbox{$^\circ$ }$ to $5\hbox {$^\circ $ }$ depending on the number of measured stars in the vicinity. A recent advance for the method has been the improvement in accuracy by the application of Hipparcos data (at least for objects with D<500 pc), this being used in the reduction scheme for most of the classical Be stars in our list. Fortunately, the average weighted values of observed polarization, $p_{\rm obs}$, for most objects in our list together with the associated $\,\sigma_{p_{\rm obs}}$were calculated recently by Heiles (2000), so considerably reducing the amount of laborious work required for the exercise. For a few stars which were investigated polarimetrically more intensively, we estimated $\sigma_{p_{\rm obs}}$, taking into account the data from recent papers of Quirrenbach et al. (1997), McDavid (1999, 2000) and Ghosh et al. (1999).

Two typical examples of the reduction scheme are presented in Fig. 1. Note that, in some cases, $\,p(D)\,$ may not display monotonic growth due to the line of sight passing through interstellar dust clouds with complex structure and different orientation of dust grains. For the cases where the distance to an object could not be determined from the Hipparcos data or the parallax errors were too large, we estimated the distance to a star either from reddening or from an absolute magnitude-spectral type/luminosity calibration. In a few cases an interstellar component has been estimated by the investigation of the uniformity of polarization vectors in the vicinity of the star. The parameters of $p_{\rm obs}$, $p_{\rm is}$ and $p_{\ast }$ for the program stars are presented in Appendix II. It is seen that except for a few stars, most values of $\sigma_{p_{\rm obs}}< 0.3\%$ and thus less than the chosen histogram binwidth.

An independent by-product of this study is the new set of estimates of interstellar polarization components, this being useful for other future investigations.

4 $\mathsf{E(V-L)}$, polarization and v sin i as a function of spectral type

4.1 The excess $\mathsfsl{E(V-L)}$ against spectral type

In Fig. 2a the values of the excess E(V-L) are plotted against spectral type for the entire sample. The following features are immediately obvious. Firstly, there is a clear upper limit for a given spectral type with the maximum value of about $1\mbox{$\,.\!\!\!^{\rm m}$ }8$ for B0-B2 stars and with the decrease of near IR excesses toward later than B2 spectral types. A similar result was obtained by Dougherty et al. (1991) who found that most of late type stars show little or no near IR excess colour but for a significantly smaller statistical sample. However, in contrast to previous studies, we conclude that the decrease of the upper limit of E(V-L)towards late spectral types is well fitted by a function in the form of an exponential decay rather than the linear decay. For the spectral interval from B1 to B9.5 the best fit is described as follows:

\begin{displaymath}E(V-L)=0.31\,+\,1.67\times\exp\left(-\frac{X-0.70}{2.94}\right)
\end{displaymath} (2)

where $\,X\,$ is the value of the spectral subtype. This fit is indicated by a solid curve in Fig. 2a with 95% of program stars of a given spectral types located below the curve. Note that approximately the same curve represents the change of the stars' effective temperatures according to spectral subtype. This behaviour is readily understandable, in general terms, as the near IR excess is dependent on the electron density in the circumstellar environment which is in turn a function of stellar temperature. Secondly, the value of IR excesses shows a larger scatter for B1-B3 spectral types. Thirdly, less than 5% of the investigated stars are above the limit (2). The discussion on the anomalous objects and the distributions of IR excesses for different spectral subgroups of Be stars will be considered in more detail in Sect. 6.
  \begin{figure}
\par\includegraphics[width=8cm,height=6cm,clip]{9470f2a.ps}\par\v...
...pace*{2.5mm}
\includegraphics[width=7cm,height=6cm,clip]{9470f2c.ps}\end{figure} Figure 2: Near IR excess E(V-L), intrinsic polarization, and $v\sin{i}$as a function of spectral type. The upper limit is indicated by the solid curve. The short-dashed curve indicates the average value of the parameters for a given spectral type. The long-dashed curve indicates the value of $T_{\rm e}$ for a given spectral type
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4.2 Polarization against spectral type

In Fig. 2b the values of $\,p_{\ast}\,$ for the entire sample are plotted against spectral type. This distribution shows a similar behaviour as for near-IR excesses. Firstly, the values show larger scatter for Be stars of earlier spectral types (B0-B3). Secondly, there is an upper limit of $\,p_{\ast}\,$ for a given spectral type. This is represented by a solid curve in Fig. 2b below which 95% of stars of the given spectral type (in the range B3-B9) are located. The upper limit is well described by a function in the form of an exponential decay:

\begin{displaymath}p_{\ast}(\%)=0.46\,+\,1.74\times\exp\left(-\frac{X-1.5}{3.22}\right)
\end{displaymath} (3)

where $\,X\,$ is the number defining the spectral subtype. The explanation of this dependence is the same as in the previous section. Thirdly, on average, Be stars of earlier spectral type exhibit larger values of polarization. Fourthly, the maximum values of intrinsic polarization for B0-B3 stars are approximately the same ( $p_{\ast}\approx2$%) and the upper limit in polarization for these stars does not correspond to the curve which represents the change of star's effective temperature according to spectral subtypes. This indicates that the behaviour "$p_{\ast }$: Sp class" for early type stars is more complicated and there are several physical parameters dictating the levels of polarization. The distributions of $\,p_{\ast}\,$ for different spectral subgroups of Be stars will be considered later in Sect. 7.

4.3 v sin i against spectral type

In Fig. 2c the values of $\,v\sin{i}\,$ are plotted against spectral type for the entire sample. First impressions suggest that there are no significant differences in $\,v\sin{i}\,$ for the subtypes of Be stars. However, there is a possible trend in the average values in the sense that later spectral type stars rotate faster than early ones. The best linear fit for this trend is:

\begin{displaymath}v\sin{i}=(204\pm5)+(2.2\pm1.2)X
\end{displaymath} (4)

where $\,X\,$ again is the value of the spectral subtype. Note, however, that this trend is not obvious for stars of III luminosity class and it is more pronounced for IV and V classes:

\begin{displaymath}{\rm III}\!:~v\sin{i}=(190\pm14)-(1.1\pm2.8)X \end{displaymath}


\begin{displaymath}{\rm IV}\!\!:~v\sin{i}=(183\pm14)+(8.0\pm3.5)X \end{displaymath}


\begin{displaymath}\ {\rm V}\!\!:~v\sin{i}=(205\pm~7)+(3.8\pm1.6)X. \end{displaymath}

The correlations for the above dependencies are small or even absent (correlation coefficients: $r=0.09\pm0.06$ for the entire sample, $-0.05\pm0.12$, $0.27\pm0.11$ and $0.14\pm0.06$ for the III, IV and V classes respectively).

The value of projected rotational velocity shows a large scatter for all Be star subspectral types but with a clear concentration around the values between 200 to 250 kms-1. All Be stars exhibit a projected rotational velocities which are less than a critical rotational velocity for the given spectral type. We will investigate the distribution of $\,v\sin{i}\,$ in more detail in the next section.

5 Distributions of projected rotational velocities

Two well-known investigations of projected rotational velocities of Be stars were completed 18 years ago (Slettebak 1982 - for a sample of 164 objects; Fukuda 1982 - for a sample of 239 objects). Slettebak noted that there are no strong differences in the rotational characteristics of Be stars of different spectral types or luminosity classes. To the contrary, Fukuda arrived at a different conclusion showing that the middle and later types rotate faster on average than early Be stars, but the influence of luminosity class was not studied. Since then, several attempts to carry out similar kinds of investigation for different samples of classical Be stars have been made with somewhat different conclusions (see, for example, Zorec et al. 1990; Balona 1990; Zorec & Briot 1997; Grady et al. 1989; Steele 1999 etc.). It is now possible to reassess the situation using the numerous and homogeneous $\,v\sin{i}\,$ data collected and reduced in the present study. We investigate here the distributions of projected rotational velocities of the program stars for four different spectral subgroups (O-B1.5, B2-B2.5, B3-B5.5 and B6-B9.5) and different luminosity classes.

Investigation of a distribution such as $\,v\sin{i}\,$ is a classical problem of mathematical statistics. In the first place, we corrected the constructed histograms from the influence of errors ( $\sigma_{v\sin{i}}$) using Eddington's algorithm (see Smart 1958). One of the distributions (viz: for the entire sample of Be stars) is presented in Fig. 3. To compare the distributions, the following parameters should be calculated and analyzed: the mean ( $\overline{v\sin{i}}$) and the root mean square deviation ($\sigma$). To calculate these parameters for a given distribution we used the weighting procedure according to the standard error associated with each contributing measurement (see, for example, Brooks et al. 1994). However, in order to make meaningful comments on the similarity or differences between the distributions, in the first place their distribution functions should be analyzed. As a first step we should try to investigate their "Normality''. If the distribution is demonstrably non-Normal, other types of function might then be considered and applied. To test for Normality, we calculated the coefficients of skewness (g1) and the coefficients of kurtosis (g2) for each of the distributions. A detailed description of this procedure has been given recently by Brooks et al. (1994) together with the analytical expressions for $\,g_{1}\,$ and $\,g_{2}\,$. We calculated unbiased estimators of these coefficients with the associated variances (see Table 1) and compared the values with those tabulated in the above mentioned paper for the 95% and 99% confidence levels. This analysis indicates immediately that all of the distributions may be considered as Normal at the 99% confidence level and thus we don't need to invoke other types of distribution functions. At this stage, we cannot say whether the high arithmetical significance of the statistics for Normality carries real physical significance in the sense that it is an expected intrinsic characteristic of the $v\sin{i}$ distributions of Be stars. Such kind investigations might be the matter of future studies.

  \begin{figure}
\par\includegraphics[width=7cm,height=7cm,clip]{9470f3.ps}\end{figure} Figure 3: Observed distribution of $v\sin{i}$ corrected from errors and its best Gaussian fit for the entire sample of Be stars. The dashed vertical line indicates the mean value of $v\sin{i}$
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The calculated parameters for each of the distributions are given in Table 1.

 

 
Table 1: Mean $\overline{v\sin{i}}$ values, $(\sigma)$, the coefficients of skewness (g1) and kurtosis (g2)of the distributions, true rotational velocities and the ratio of $\overline{v\sin{i}}/\overline{v_{\rm c}}$ and $\overline{v_{\rm t}}/\overline{v_{\rm c}}$ for different spectral subgroups and different classes of luminosity of Be stars

III, III-IV classes luminosity
spectral range: O-B1.5 B2-B2.5 B3-B5.5 B6-B9.5 O-B9.5
N stars: 37 30 28 40 135
$\overline{v\sin{i}}$, (kms-1) $203\pm11$ $211\pm10$ $192\pm14$ $207\pm10$ $201\pm~6$
$\sigma$ $70\pm~5$ $78\pm~4$ $89\pm~6$ $63\pm~5$ $74\pm~8$
g1 $-0.326\pm0.158$ $0.314\pm0.162$ $0.137\pm0.182$ $-0.234\pm0.143$ $-0.001\pm0.042$
g2 $1.998\pm0.605$ $2.441\pm0.621$ $2.454\pm0.693$ $2.653\pm0.549$ $2.412\pm0.164$
$\overline{v_{\rm c}}$, (kms-1) 456 408 383 320 385
$\overline{v\sin{i}}/\overline{v_{\rm c}}$ 0.45 0.52 0.50 0.65 0.52
$\overline{v_{\rm t}}$, (kms-1) 259 269 245 264 259
$\overline{v_{\rm t}}/\overline{v_{\rm c}}$ 0.57 0.66 0.64 0.83 0.67

IV-V, V classes luminosity
spectral range: O-B1.5 B2-B2.5 B3-B5.5 B6-B9.5 O-B9.5
N stars: 66 78 78 61 283
$\overline{v\sin{i}}$, (kms-1) $202\pm~9$ $207\pm~8$ $236\pm~7$ $243\pm~8$ $229\pm~4$
$\sigma$ $80\pm~9$ $77\pm~6$ $41\pm~6$ $58\pm~5$ $72\pm~7$
g1 $0.188\pm0.087$ $0.040\pm0.074$ $-0.586\pm0.074$ $-0.353\pm0.094$ $-0.195\pm0.021$
g2 $2.924\pm0.339$ $2.808\pm0.290$ $4.005\pm0.290$ $2.802\pm0.365$ $2.863\pm0.083$
$\overline{v_{\rm c}}$, (kms1) 527 479 448 398 464
$\overline{v\sin{i}}/\overline{v_{\rm c}}$ 0.38 0.43 0.53 0.61 0.49
$\overline{v_{\rm t}}$, (kms-1) 257 264 300 309 292
$\overline{v_{\rm t}}/\overline{v_{\rm c}}$ 0.49 0.55 0.67 0.78 0.63

all classes luminosity (CL) including the stars with undefenite CL
spectral range: O-B1.5 B2-B2.5 B3-B5.5 B6-B9.5 O-B9.5
N stars: 106 116 121 120 463
$\overline{v\sin{i}}$, (kms-1) $201\pm~7$ $205\pm~7$ $241\pm~6$ $225\pm~6$ $219\pm~3$
$\sigma$ $74\pm~4$ $72\pm~5$ $59\pm~5$ $57\pm~4$ $70\pm5$
g1 $0.392\pm0.055$ $0.110\pm0.050$ $-0.400\pm0.048$ $-0.234\pm0.049$ $-0.043\pm0.013$
g2 $3.333\pm0.216$ $2.666\pm0.198$ $2.995\pm0.191$ $2.971\pm0.192$ $2.877\pm0.051$
$\overline{v_{\rm c}}$, (kms-1) 502 458 429 362 436
$\overline{v\sin{i}}/\overline{v_{\rm c}}$ 0.40 0.45 0.56 0.62 0.50
$\overline{v_{\rm t}}$, (kms-1) 256 261 307 288 280
$\overline{v_{\rm t}}/\overline{v_{\rm c}}$ 0.51 0.57 0.72 0.80 0.64

the data from Slettebak 1982
spectral range: B0-B1.5 B2-B2.5 B3-B5.5 B6-B9.5  
N stars: 25 35 51 54  
$\overline{v\sin{i}}$, (kms-1) 236 193 221 228  

the transformed data from Fukuda 1982
spectral range: B0-B1.5 B2-B2.5 B3-B5.5 B6-B9.5 O-B9.5
N stars: 69 63 50 57 239
$\overline{v\sin{i}}$, (kms-1) 189 196 239 244 214

the data from Zorec & Briot 1997
spectral range: B0-B1.5 B2-B3 B4-B7 B8-B9.5  
$\overline{v_{\rm t}}$, (kms-1) (II-III, III, III-IV classes) 230 190 220 130  
$\overline{v_{\rm t}}$, (kms-1) (V class) 240 250 250 280  

the data from Grady et al. 1989
spectral range:       B6-B9.5  
N stars:       40  
$\overline{v\sin{i}}$, (kms-1)       226  



 

 
Table 2: The values of $v_{\rm c}$ for Be stars of different spectral subtypes and class luminosity

Spectral type:
O8 O9 B0 B0.5 B1 B1.5 B2 B2.5 B3 B4 B5 B6 B7 B8 B9
$v_{\rm c}$, III class (kms-1): 500 460 430 412 395 383 365 355 340 325 310 295 284 275 270
$v_{\rm c}$, IV class (kms-1): 600 560 520 502 483 465 445 435 420 400 386 374 362 352 344
$v_{\rm c}$, V class (kms-1): 626 596 565 540 520 500 483 470 460 442 425 410 400 396 391


It is of interest also to compare the parameters of distributions of true rotational velocities which are easily calculated by the method suggested by Chandrasekhar & Münch (1950). In the case of randomly oriented stellar rotation axes, the mean true rotational velocity may be calculated by a simple equation: $\overline{v}_{\rm t}=\frac{4}{\pi}\overline{v\sin{i}}$.

To test the differences between the dispersions, we can use Fisher's criterion (F-test). Simple calculations indicate that for the III-IV luminosity classes, the differences between the dispersion for the distributions are statistically insignificant at the 95% confidence level (except late type stars). For the V class, it was found that the difference in $\sigma$ is significant at 95% confidence level between O-B2.5 and B3-B9 spectral subgroups.

As the next step, we may compare the mean values of $\overline{v_{\rm t}}$ and the ratio of $\,\overline{v_{\rm t}}/v_{\rm c}\,$ for selected subgroups. It is well known that the mean true velocities and critical velocities are very different, depending on the luminosity class and spectral class (see for example Zorec et al. 1990). For our purposes we interpolated/extrapolated the values of $\,v_{\rm c}\,$ from Moujtahid et al. (1999) and Zorec (2000) and present them in Table 2. The values of $\overline{v_{\rm c}}$ for given spectral subgroups (presented in Table 1) have been calculated taking into account the specific population of stars of different spectral subtypes and luminosity classes in a subgroup. Simple calculations indicate that the differences between the mean values of $\overline{v_{\rm t}}$ (or $\overline{v\sin{i}}$) for all spectral subgroups of III-IV luminosity classes are insignificant. There is, however, a pronounced trend in the ratio $\,\overline{v_{\rm t}}/v_{\rm c}\,$ for these stars. For the V class, no differences were found between the O-B1.5 and B2-B2.5 subgroups, as well as between subgroups B3-B5.5 and B6-B9.5. Nevertheless, for the subgroups O-B2.5 and B3-B9.5, there is strong statistically significant difference at the 99% confidence level in agreement with the result of Fukuda (1982) who found a clear distinction in $v\sin{i}$between B2 and B3 stars. For reference, we present in Table 1 the $\overline{v\sin{i}}$ data from other sources. The data of Fukuda (1982) (from his Table 5) were transformed into the "new'' Slettebak's scale. As follows from Table 1, most early determined values are in agreement (in general) with our data (obtained with 2 to 3 times better statistical quality).

We confirm that late type Be stars rotate faster on average than early types and the trend in the ratio $\,\overline{v_{\rm t}}/v_{\rm c}\,$ (see Table 1) is also real. We conclude that late type Be stars of all luminosity classes rotate closer to their critical break-up velocity. Whether these differences have affect on the physical characteristics of CS envelopes, or not, will be considered in Sect. 8.

Finally, it was found that the ratio $\overline{v\sin{i}}/v_{\rm c}$ (or $\,\overline{v_{\rm t}}/v_{\rm c}\,$) increases from dwarfs to sub-giants/giants for early spectral type stars (O-B1.5 and B2) though not obvious for middle and late spectral types (see Table 1). This clearly contradicts the results of Steele (1999) who investigated a small sample of Be stars separated into three subgroups according to the luminosity class (III, IV, V-13, 8 and 34 objects respectively). Although our statistical study for sub-giants and giants is also not based on a large sample (135 objects), the behaviour is clearer for the sequence of ${\rm V}\rightarrow {\rm IV}\rightarrow {\rm III}$ luminosity classes (see Table 3). This phenomenon can be easily explained in terms of a more rapid evolution of high-mass stars and the acceleration of their rotation. The main sequence lifetime is significantly shorter for B0 stars than for B9 stars (see, for example, Bisnovatyi-Kogan 1989). It may be supposed that most of O-B1.5 and B2 stars of III and IV luminosity classes are possibly in the secondary contraction phase but, on average, the late spectral type stars are not.


 

 
Table 3: The values of $v\sin{i}/v_{\rm c}$ for Be stars of different spectral subtypes and classes luminosity

Spectral type:
O-B1.5 B2-B2.5 B3-B5 B6-B9
$v\sin{i}/v_{\rm c}$, V class: 0.38 0.43 0.53 0.61
$v\sin{i}/v_{\rm c}$, IV class: 0.43 0.49 0.50 0.64
$v\sin{i}/v_{\rm c}$, III class: 0.46 0.56 0.51 0.65


6 Distributions of near and far IR excesses

As already mentioned, a detailed study of near IR excesses of classical Be stars was undertaken by Dougherty et al. (1994). They used near IR excesses for a sample of 144 Be stars (115 stars with E(V-L) data) for statistical analysis. One of the conclusions was that the excess increases with wavelength and 60% of Be stars exhibit a significant excess in the L band. They also found a bi-modal distribution of the excesses for the wavelengths greater than 2.2 $\mu $m but they did not study this behaviour in detail. For this reason, we investigate here the distributions of E(V-L)colour excesses. We have collected the data of V and L photometry for $\approx$200 stars and, for an additional 40 stars, the values of E(V-L)were estimated by an extrapolation of JHK data. Thus, by essentially doubling the size of the data base over Dougherty et al. (1994), we are able to compare the E(V-L) distributions for different subgroups of Be stars.

  \begin{figure}
\par\includegraphics[width=7.8cm,height=4.5cm,clip]{9470f4a.ps}\p...
...ce*{2mm}
\includegraphics[width=7.8cm,height=4.5cm,clip]{9470f4d.ps}\end{figure} Figure 4: Observed distributions of E(V-L) (corrected for errors) for different subgroups of Be stars. The short-dashed and long-dashed vertical lines indicate the positions of two peaks for a bi-modal Gaussian distribution
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Note, however, that 6 stars were excluded from the statistical analysis due to their unexpectedly large near IR excess for their spectral type (see Fig. 2a). Some comments on their characteristics and evolutionary status are given below. First of all, the values of near IR excess, $E(V-L)>2^{\rm m}$, are difficult to explain in a framework of free-free, free-bound emission and such large values require the presence of a dust component in CS environment. Thus, the star HD 181615 (B2Vpe, $E(V-L)=3\mbox{$\,.\!\!\!^{\rm m}$ }03$) is likely to contain CS dust. The conclusion on the presence of the dust emission is very likely for the stars HD 50123 (B6IVe, $1\mbox{$\,.\!\!\!^{\rm m}$ }42$), HD 51480 (B8e, $1\mbox{$\,.\!\!\!^{\rm m}$ }53$), both exhibiting also an excess at 12 $\mu $m larger than the upper limit for Be stars of a given spectral type (Coté & Waters 1987). Note that 51 Oph (B9.5V), HD 164906 (B1IV:) and HD 38087 (B5Ve), exhibit unusual far IR excess ( $3\mbox{$\,.\!\!\!^{\rm m}$ }7$, $4\mbox{$\,.\!\!\!^{\rm m}$ }98$ and $3\mbox{$\,.\!\!\!^{\rm m}$ }79$ at 12 $\mu $m respectively). Relative to classical Be stars, this also indicates the presence of dust emission. An inspection of the lists of Coté & Waters (1987) and Oudmaijer et al. (1992) shows that only a few Be stars from about 150 objects show excess emission with $E(V-12)>3^{\rm m}$ and some of them are definitely young objects. Thus, the value $E(V-12)\approx3^{\rm m}$ is a limit for free-free and free-bound emission in the CS environment of classical Be stars. The evolutionary status of two other objects: HD 177291 (B8Ve, $1\mbox{$\,.\!\!\!^{\rm m}$ }44$) and HD 81357 (B8Ve, $1\mbox{$\,.\!\!\!^{\rm m}$ }5$) is not clear. However, the latter star has been classified recently as a binary with an F/G secondary (Halbedel 1996) whose light contribution may give an increase to the observed E(V-L) excess.

The distribution of E(V-L) for the entire sample shows the same bi-modal shape behaviour as described by Dougherty et al. (1994) but in a more pronounced form. We performed the same procedure for error correction of the histograms as in the previous section.

 

 
Table 4: Parameters of distributions of near IR E(V-L) and far IR E(V-12) excesses (in magnitudes) for different subgroups of Be stars

Subgroup:
O-B1 B2 B3-B5 B6-B9

N stars:
57 59 58 67
$\overline{E(V-L)}$ 0.93 0.72 0.41 0.17

N stars:
29 38 38 40
$\overline{E(V-12)}$ 1.90 1.59 1.39 0.72

Parameters of bi-modal Gaussian fits for E(V-L)
Peak 1: $\bar{x}_{1}$ $0.32\pm0.05$ $0.24\pm0.03$ $0.16\pm0.02$ $0.16\pm0.01$
Peak 1: $\sigma_{1}$ $0.12\pm0.02$ $0.14\pm0.03$ $0.20\pm0.01$ $0.16\pm0.02$
Peak 2: $\bar{x}_{2}$ $1.30\pm0.07$ $0.92\pm0.04$ $0.80\pm0.05$  
Peak 2: $\sigma_{2}$ $0.37\pm0.08$ $0.37\pm0.05$ $0.11\pm0.04$  

Parameters of bi-modal Gaussian fits for E(V-12)
Peak 1: $\bar{x}_{1}$ 0.75 ? $0.80\pm0.05$ ? $0.71\pm0.06$
Peak 1: $\sigma_{1}$   $0.27\pm0.04$   $0.30\pm0.04$
Peak 2: $\bar{x}_{2}$ $2.07\pm0.06$ $2.05\pm0.04$ $1.83\pm0.05$  
Peak 2: $\sigma_{2}$ $0.27\pm0.05$ $0.32\pm0.04$ $0.30\pm0.07$  


Firstly, late spectral type stars exhibit smaller values of E(V-L) on average (see Table 4), this already mentioned in Sect. 4 and noted earlier by Dougherty et al. (1991, 1994), possibly due to a lower electron density in their CS environment. It is obvious from Fig. 4 and in Table 4, that a bi-modal form is present for the first three spectral subgroups of Be stars (O-B1.5, B2-B2.5 and B3-B5.5). For these subgroups, the mean values of E(V-L) corresponding to the first peak are approximately the same, within the length of the sampling step, with $\overline{E(V-L)}_{\rm peak 1}\approx0\mbox{$\,.\!\!\!^{\rm m}$ }22\pm0\mbox{$\,.\!\!\!^{\rm m}$ }08$. Statistical analyses, similar to those made in previous section, indicate that all the distributions may be well approximated by a bi-modal Gaussian form. This bi-modality for O-B1.5, B2-B2.5 and B3-B5.5 spectral subgroups is confirmed to a 99% level of confidence. We performed a more detailed study of the B3-B5.5 spectral subgroup and found that a bi-modal distribution is present for B3 type stars with two peaks centered at $0\mbox{$\,.\!\!\!^{\rm m}$ }15\pm0\mbox{$\,.\!\!\!^{\rm m}$ }16$ and $0\mbox{$\,.\!\!\!^{\rm m}$ }87\pm0\mbox{$\,.\!\!\!^{\rm m}$ }21$), but bi-modality is not present for B4-B5 stars. For B6-B9.5 stars, the distribution also does not exhibit bi-modality and the mean value of E(V-L) for the best simple Gaussian fit is the same as the first peaks for other subgroups.

  \begin{figure}
\par\includegraphics[width=8cm,height=7cm,clip]{9470f5.ps}\end{figure} Figure 5: Observed distributions of E(V-12) (corrected from errors) for the entire sample of Be stars. The short-dashed and long-dashed lines indicate the position of two peaks for a bi-modal Gaussian distribution
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  \begin{figure}
\par\includegraphics[width=7.8cm,height=4.5cm,clip]{9470f6a.ps}\p...
...ce*{2mm}
\includegraphics[width=7.8cm,height=4.5cm,clip]{9470f6d.ps}\end{figure} Figure 6: Observed distributions of E(V-12) (corrected from errors) for different subgroups of Be stars. The short-dashed and long-dashed lines indicate the positions of the two peaks for a bi-modal Gaussian distribution
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The important difference between the various bi-modal distributions is that the second peak has its maximum at different values of E(V-L). The behaviour is that for early spectral types, the second peak appears at larger values of E(V-L). This difference is clearly obvious in a numerical form in Table 4 where the parameters of these distributions are given. Using a t-test and T-test, it is easy to demonstrate that the differences between the positions of the second peaks are statistically significant at the 99% confidence level. Note that, for the optically thin case, the excess emission in the near IR is proportional to the emission measure which is a function of the mean electron density in formation regions and the ionizing stellar fluxes. It is easy to show from our data that the changes in $E(V-L)_{\rm peak 2}$ may be well described by a linear function of $\log\overline{T_{\rm eff}}$ in the form: $E(V-L)_{\rm peak 2}\approx{-11.1}+2.78\log\overline{T_{\rm eff}}$. The predicted $E(V-L)_{\rm peak 2}$ values correspond well to the observed values.

  \begin{figure}
\par\includegraphics[width=7.8cm,height=7.2cm,clip]{9470f7.ps}\end{figure} Figure 7: E(V-12) colour excess versus spectral type for the entire sample of Be stars. The upper limit is indicated by the solid line. The long-dashed line indicates the value of $T_{\rm e}$ for a given spectral type
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It is of interest to compare the behavior of E(V-L) with that for far IR excesses at $12~\mu$m. Dougherty et al. (1994), with the reference to a private communication of Waters, mentioned the presence of bi-modality of the E(V-12) distribution for Be stars. To check this suggestion we constructed the similar diagrams for E(V-12). Although bi-modality is clearly seen for the entire sample of Be stars (Fig. 5), it reflects rather the different contributions of early and late type stars. Our sample is insufficiently large to provide any conclusion on bi-modality for different spectral subgroups. Slight evidence of two peaks in the E(V-12) distribution exists only for B2 stars (see Fig. 6). An important point, however, is that the average value of $\overline{E(V-12)}$ and the position of the maximum peak in the distributions is not significantly different between the first three subgroups (see Table 4). Coté & Waters (1987) considered the far IR data for a sample of 101 Be stars and found the constant upper limit in E(V-12) for stars earlier than B3. The same conclusion follows from the analysis of our data for 150 objects (see Fig. 7). This indicates that the characteristics of the outer parts of CS envelopes are similar for early and middle spectral type stars. For the majority of Be stars, with the excess emission increasing with wavelength, the CS envelopes must become optically thick from at least $\lambda > 10~\mu$m (Gehrz et al. 1974). With this assumption, for any kind of geometry for the CS environment, the excess E(V-12) is proportional to the effective surface area of the emitting region. It is easy to show that the relation between the upper limit of the excess E(V-12)and $T_{\rm e}$ will be fairly linear for B3-B9 stars in contrast to the E(V-L): $T_{\rm e}$ relation. But the behaviour in early type stars is more complicated.

An unresolved point is the nature of the peak 1 in the E(V-L) distributions for early and intermediate spectral type stars. There are several possibilities to explain the value of $E(V-L)\approx 0$ for some objects:

a) there are many Be stars surrounded by small CS envelopes indicated by low emission in H$\alpha$;
b) the photometric data of V and L used for calculation of the E(V-L) excesses were obtained mainly non-simultaneously;
c) spectral classification of some early type stars can be dubious.

For case (a), we would expect a lower $\,p_{\ast}\,$ values for the stars which are concentrated under peak 1. Although the analysis of our data shows some decrease in the polarization level for such stars in comparison with peak 2, the difference in $\overline{p_{\ast}}$ for the two peaks is small and insignificant (see Table 5).

 

 
Table 5: Differences in the level of intrinsic polarization for the stars in the peak 1 and peak 2 of the E(V-L) distributions
  Subgroup: O-B1 B2 B3-B5
 

peak 1 peak 2 peak 1 peak 2 peak 1 peak 2
  $E(V-L)<0\mbox{$\,.\!\!\!^{\rm m}$ }85$ $E(V-L)>0\mbox{$\,.\!\!\!^{\rm m}$ }85$ $E(V-L)<0\mbox{$\,.\!\!\!^{\rm m}$ }4$ $E(V-L)>0\mbox{$\,.\!\!\!^{\rm m}$ }5$ $E(V-L)<0\mbox{$\,.\!\!\!^{\rm m}$ }4$ $E(V-L)>0\mbox{$\,.\!\!\!^{\rm m}$ }5$
N stars: 26 26 16 38 26 20
$\overline{p_{\ast}}$, % 0.57 0.85 0.52 0.63 0.42 0.52


For the cases (b) and (c), we would expect a more single-peaked distribution with more extended tails rather than a bi-modal distribution. Finally, it should be remembered that each Be star can show at any time one of the phases - normal B $\Leftrightarrow$ Be $\Leftrightarrow$ Be-shell. These phases are characterized by different spectral behaviours (a normal absorption-line spectrum or emission/shell spectrum) due to changes of electron density and/or of geometry of the CS envelopes (Doazan et al. 1988). There is no doubt that during the normal B phase, the electron density is too small to produce any considerable IR excess. According to Dougherty et al. (1994), for the IR excess in the L-band to be detectable, the density of the CS plasma has to be $\approx$ $10^{-11.6}~{\rm g\,cm}^{-3}$. To account for the maximum level of $p_{\ast}\approx0.5\ {\rm to}\ 1\%$ observed for the stars under peak 1 (with the above value of density and typical sizes of CS environment $\approx$ $10\ {\rm to}\ 15~R_{\ast}$), in the framework of the disk model, the half-opening angle of the disk cannot be smaller than 10$^\circ$ to 15$^\circ$. The important point is that in order to explain a bi-modal character of the distributions, one can suggest that the transition time between the normal B and Be/Be-shell phases is much shorter than the duration of the phases themselves. In this case, we can observe an object either at the normal B phase (with $E(V-L)\approx 0$) or at the Be/Be-shell phase with E(V-L) values from the distribution under peak 2. In principle, our suggestion is supported by the data of Doazan et al. (1986), who found significant spectral variations in $\theta$ CrB on a time scale of 3 months when the star changed its phase from shell to normal. At the same time, the duration of the phases in Be stars (or an envelope lifetime) is typically of the order of decades (Cramer et al. 1995; Fox 1991). Our suggestion is consistent also with the hypothesis that the formation of CS envelopes in Be stars is due to short lasting huge mass ejections (Hubert & Floquet 1998; Moujtahid et al. 1999; Zorec et al. 2000a, 2000b). All the above may be also valid to explain bi-modality in E(V-12) distributions (if it exists). Hubert-Delplace et al. (1981) and Mennickent et al. (1994) noted that the time scale of phase transitions is shorter in early-type Be stars than in late spectral types. Thus we would expect less pronounced bi-modality in late types too, this not being obvious in our data. The apparent absence of bi-modality for late spectral types (B4-B5 and B6-B9.5) can be explained by the notion that the second peak would be placed toward smaller values of E(V-L). Its possible location is perhaps masked by a combination of the chosen binwidth in association with the small statistical sample.

7 Distributions of intrinsic polarization for different subgroups of Be stars

As was noted before, (see Sect. 4.1 and Fig. 2b), Be stars of earlier spectral type tend to exhibit larger values of intrinsic polarization. Thanks to the large bank of calculated values of $p_{\ast }$ ($\approx$500 objects), it is possible to investigate the above mentioned behaviour in detail.

 

 
Table 6: Intrinsic and true polarization for different spectral subtypes and subgroups of Be stars

Spectral type:
O-B0 B1 B2 B3 B4 B5 B6 B7 B8 B9  
No. of stars: 47 118 146 58 22 25 20 23 23 11  

$\overline{p_{\ast}}$, (%)
0.83 0.85 0.75 0.59 0.52 0.48 0.47 0.45 0.29 0.22  
$\overline{p}_{\rm t}$, (%) 1.25 1.28 1.13 0.88 0.78 0.72 0.70 0.67 0.43 0.33  

Spectral range
O-B1.5 B2-B2.5 B3-B5.5 B6-B9.5 O-B9.5
No. of stars: 166 146 105 77 495
$\overline{p_{\ast}}$, (%); $\sigma_{\rm p}$ 0.84   0.48 0.75   0.48 0.55   0.48 0.37   0.28 0.68   0.48
$\overline{p}_{\rm t}$, (%) 1.27 1.13 0.82 0.56 1.02


Analysis of the intrinsic polarization distribution for classical Be stars was first performed by McLean & Brown (1978) for a sample of 67 objects. They noted a rapid rise of the distribution toward smaller values of $\,p_{\ast}$. The distribution established here (corrected for errors) for a sample of 495 objects (see Fig. 8) is similar to that obtained by McLean & Brown (1978). However, with the chosen binwidth (0.3%), our distribution peaks at $p_{\ast}\approx 0.4\%$ with the average weighted value $\overline{p_{\ast}}= 0.68\%$ and $\sigma_{\rm p}=0.48\%$. Our large sample allows us also to study for the first time the distributions of $\,p_{\ast}\,$ for the representative samples of Be stars of different spectral subgroups. These distributions, also error corrected, are shown in Figs. 9a-c. For O-B1.5 stars we used a slightly larger binwidth (0.35%) because of the possibly larger uncertainties in determination of interstellar components. It is clearly seen that the histograms are significantly different for each spectral subgroup. In contrast to late type stars, the distributions for early spectral types (O-B1.5 and B2-B2.5) do not peak at the value $p_{\ast}\approx 0\%$. This result is significant in spite of the relatively large standard deviations (see Table 6). Similar to the analysis for E(V-L) distributions, we performed a more detailed study of the B3-B5 spectral subgroup and found again that such behaviour is present with just B3 stars, but it disappears for B4-B5 stars.

  \begin{figure}
\par\includegraphics[width=7cm,height=7cm,clip]{9470f8.ps}\end{figure} Figure 8: Distribution of intrinsic polarization (corrected for errors) for the entire sample of Be stars. The vertical dashed line indicates the mean value of polarization
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  \begin{figure}
\par\includegraphics[width=7.1cm,height=4cm,clip]{9470f9a.ps}\par...
...pace*{2mm}
\includegraphics[width=7.1cm,height=4cm,clip]{9470f9d.ps}\end{figure} Figure 9: Distributions of intrinsic polarization (corrected for errors) for different spectral subgroups of Be stars. The vertical dashed line indicates the mean value of polarization
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A clear difference in the values of $\,\overline{p_{\ast}}\,$ for different spectral subtypes and subgroups is apparent in the sense that there is a decrease in mean values of intrinsic polarization toward late spectral types (see Table 6). Physically this fact has been discussed previously by McLean & Brown (1978) in terms of less dense and/or less oblate envelopes for later stars. Application of various tests indicates that differences in the mean values of intrinsic polarization for different subgroups of Be stars are statistically significant. McLean & Brown (1978) found that there are no objects among Be stars with the intrinsic polarization in excess 2%. Our data allow us to study this suggestion statistically. Only 5 stars out of 497 objects (i.e. about 1%) show $p_{\ast}>2$% and 5 stars additionally exhibit $p_{\ast}=2$% (all of them are early type stars B0-B2). Moreover, we conclude that about 95% of Be stars exhibit intrinsic polarization on the level $0\% < p_{\ast} < 1.5\%$. This result is very important because Waters & Marlborough (1992) noted that in a framework of the single-scattering approximation (and geometrically thin disks, $\Theta\approx15\hbox{$^\circ$ }$) it is difficult to obtain high levels of polarization above 2%. The observed level of polarization can be explained either by a disk of large optical depth and a small opening angle or by a wide disk (or an ellipsoidal envelope) of small optical depth. To explain the polarization up to 3%, multiple scattering is considered in the series of the papers of Wood et al. (1996a, 1996b, 1997) and early by Daniel (1980). Nevertheless, there is much evidence that CS envelopes are optically thin, at least up to $\lambda\approx~10~\mu$m (see, for example, Gehrz et al. 1974); this also follows from multicolour IR polarimetry of some Be stars by Jones (1979) (as the position angle does not change from the visual to 2.2 $\mu $m). From comparisons of position angles of CS disks derived from optical interferometry and intrinsic position angles of polarization for seven Be stars, Quirrenbach et al. (1997) reached the same conclusion. As follows from our analysis, the percentage of Be stars with $p_{\ast}>1.5$% is negligible and multiple scattering (and strongly flattened disks: $\Theta<5\hbox{$^\circ$ }$ and $\tau>1$) may occur only in a few objects. Note that the upper limit in intrinsic polarization can be larger if we consider the true polarization by removing the aspect angle effect, using the method suggested by McLean & Brown (1978): $\overline{p}_{\rm t}=\frac{3}{2}\overline{p_{\ast}}$. For reference, the parameters of true polarization for Be stars of different spectral subtypes and subgroups are also given in Table 6. Even in this case, however, the fraction of Be stars with $p_{\rm t}>2$% does not exceed 10%.

The next point to consider is the possible differences in polarization of Be and Be-shell stars. This comparison is quite important as there is active debate on the change in the structure of CS envelopes of Be and Be-shell stars (Marborough et al. 1993; Hanuschik 1996; van Kerkwijk et al. 1995). It was found earlier that for some objects, the level of polarization increases when a star goes through a shell phase (Arsenijevic et al. 1987). Using a small statistical sample, Fox (1993b) noted a little higher level of polarization of Be-shell stars (12 objects, $0.77\pm0.41\%$) in comparison with non-shell stars (21 objects, $0.42\pm0.39\%$) (note, however, the magnitudes of the errors). On the other hand, Ghosh et al. (1999) found no distinction in polarization level between 24 Be and 5 Be-shell stars. Using the data of Hanuschik (1996) we are able to identify 46 Be-shell stars which have shown shell characteristics at some point in their observed history and compare their behaviour with others. The average values of the parameters for non-shell stars have been calculated using the data from Tables 4 and 6 for the same specific population of stars of different spectral subtypes as in the shell subgroup. As follows from Table 7, no differences (in polarization and IR excesses) exist between Be non-shell and Be-shell stars. A compilation of polarimetric data for Pleione (see WUPPOL 1999) for different phases (Be and Be-shell) also shows the absence of a significant changes in the polarization level. This suggests that the phase transition Be $\Leftrightarrow$ Be-shell has no strong affect on the parameters describing the inner parts of the disks. Note, however, that all Be-shell stars show significant variability in photometry and polarimetry and the averaging over a long period is not a correct procedure. For this reason, the above discussion can be considered as only a preliminary suggestion. A statistical analysis of the rotational characteristics of Be-shell stars is much more informative as their $v\sin{i}$ values do not depend on the phase changes. In this context it is interesting to investigate an inclination aspect of Be and Be-shell stars as discussed earlier by Moujtahid et al. (1999). Although the errors are large, the mean viewing angle ("i'') of Be-shell stars derived from the ratio $\overline{v_{\rm t}}/\overline{v_{\rm c}}$ is larger on average than that for other Be stars ( $52\hbox{$^\circ$ }\pm20\hbox{$^\circ$ }$ and $40\hbox{$^\circ$ }\pm19$ respectively). Thus, Be-shell stars are viewed closer to the CS disk plane and none of them are observed at the angle less than $30\hbox{$^\circ$ }$.

 

 
Table 7: Differences in the observed characteristics of Be-shell and Be stars. The number of stars (N) used to calculate the average values of the parameters is indicated in parentheses

$p_{\ast }$ E(V-L) E(V-12)

Be-shell (N stars)
0.61$\%$(44) $0\mbox{$\,.\!\!\!^{\rm m}$ }61$(40) $1\mbox{$\,.\!\!\!^{\rm m}$ }49$(31)
non-shell (N stars) 0.57$\%$(448) $0\mbox{$\,.\!\!\!^{\rm m}$ }47$(203) $1\mbox{$\,.\!\!\!^{\rm m}$ }34$(119)


On the other hand, there is clear difference in average values of "i'' between Be-shell stars of different spectral subgroups:
O9-B1.5:   $42\hbox{$^\circ$ }\pm12\hbox{$^\circ$ }$       B2-B2.5:   $41\hbox{$^\circ$ }\pm10\hbox{$^\circ$ }$
B3-B5.5:   $59\hbox{$^\circ$ }\pm18\hbox{$^\circ$ }$       B6-B9.5:   $55\hbox{$^\circ$ }\pm17\hbox{$^\circ$ }$.
If the transition to the Be-shell phase is due to mass loss preferably close to a CS disk plane, the opening angle of CS disks may be smaller for late type stars.

The last point for consideration is a deviation of the distribution peaks from $p_{\ast}=0\%$ for early type stars. Although the problems in detection of the peak in a distribution with very small values of p are discussed by McLean & Brown (1978), the differences detected here are probably real. The first possibility to explain the behaviour is that most early type stars in our sample are more distant objects. The estimates of interstellar components for them are not so precise, so that the displacement from 0% can be attributed to inaccuracy of its removal. On the other hand, the behaviour can be explained if the suggestion on the randomly oriented rotation axes of envelopes is not true. This point will be discussed in a separate paper. Finally, it may be due to more complicated geometries associated with the CS environments of early-type stars.

8 Discussion

An excellent discussion on the problems of analysis of the polarization distribution of classical Be stars has been presented by McLean & Brown (1978), and a detailed discussion of near and far IR characteristics was made by Coté & Waters (1987) and Dougherty et al. (1991, 1994). Such kind of theoretical work is beyond the purpose of our paper and we will discuss some of our results only briefly. Our very large statistical sample allows us to explore possible correlations between the parameters discussed here and to make some suggestions on CS envelope geometries.

First, no clear correlations exist between the intrinsic polarization and near IR excesses neither for a sample of 209 stars (see Fig. 10a) nor for different spectral subgroups.

  \begin{figure}
\par\includegraphics[width=7.2cm,height=6.8cm,clip]{9470f10a.ps}\...
...e*{2mm}
\includegraphics[width=7.2cm,height=6.8cm,clip]{9470f10b.ps}\end{figure} Figure 10: Correlation between near a) and far b) IR excesses and intrinsic polarization for the entire sample of Be stars
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This negative result is very important because it indicates that the regions in CS envelopes which are responsible for generating the polarization and near IR excesses are different. Note that Coté & Waters (1987) and Waters & Marlborough (1992) found and discussed a possible correlation between the polarization and far IR excesses at 12 $\mu $m, but on the basis of very small sample (46 stars). To study this suggestion, we investigated the correlation between the values of polarization and the excesses at 12 $\mu $m (E(V-12)) for 125 Be stars. The data of E(V-12)were taken from Coté & Waters (1987) and Oudmaijer et al. (1992). A comparison of Figs. 10a and 10b indicates that, in contrast to near IR excesses, the relation between the intrinsic polarization and far IR excesses, with a factor three improvement of sample size, really exists in the form of a triangular shaped distribution similar to that found by Coté & Waters (1987). With a few exceptions (6 stars, three of them Be-shell), there are no stars with high polarization and low far IR excesses. The well defined upper limit is described by the empirical relation:

\begin{displaymath}{p}^{V}_{\ast}=0.65\times E(V-12).
\end{displaymath} (5)

Note that Coté & Waters (1987) plotted B band values of $p_{\ast }$ against E(V-12) and the upper limit for their dependence is described by ${p}^{B}_{\ast}=0.83\times E(V-12)$. The ratio of pB/pV, however, is virtually constant for all classical Be stars (see, for example, Ghosh et al. 1999) and is equal to $1.28\pm0.09$. Taking into account this ratio, we conclude that the upper limits for our dependence and for the dependence of Coté & Waters (1987) are exactly the same. Reasons for the lack of correlations between $p_{\ast }$ and E(V-L) in contrast to the $p_{\ast }$: E(V-12) triangular distribution is not clear. As noted by Poeckert & Marlborough (1976) and Coté & Waters (1987), the bulk of the polarization is produced in layers within <3 $R_{\ast}$, while the 12 $\mu $m excess can originate from layers that are further out. However, it was shown recently by Fox (1993b), that two parameters are important for continuum linear polarization in Be stars: the envelope oblateness and the location of the inner boundary of the cool extended envelope (which is typically $\approx$$R_{\ast}$). The behaviour seen in Fig. 10b does not contradict to the suggestion that $p_{\ast }$originates in those regions of CS envelopes which are optically thin. It may reflect a link between far IR excesses (or polarization) and the size of CS envelopes.

Note that although the correlation between near and far IR excesses clearly exists (with a correlation coefficient of $r=0.65\pm0.06$), there is a significant scattering of the data points (see Fig. 11).

  \begin{figure}
\par\includegraphics[width=7.2cm,height=6.8cm,clip]{9470f11.ps}\end{figure} Figure 11: Correlation between near and far IR excesses for the entire sample of Be stars. The dashed lines represent a possible non-linear fit for the observational data for E(V-L): $E(V-m_{\lambda }$) dependencies where $m_{\lambda }$ is the magnitude at 12 $\mu $m, 25 $\mu $m and 60 $\mu $m respectively. The data points marked in this figure concern E(V-L) and E(V-12) data
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The large spread is difficult to explain if near and far IR excesses arise in the same gaseous disks and have the same nature (free-free and free-bound radiation). The correlation coefficients for different spectral subgroups show an increase toward late spectral type stars ( $r=0.36\pm0.14$, $0.55\pm0.14$ and $0.66\pm0.11$ for B2, B3-B5 and B6-B9 respectively). For O-B1.5 stars, $r=0.71\pm0.14$ but the statistical sample is too small (13 objects). Moreover, a visual inspection of Fig. 11 leads to the suggestion that the dependence E(V-L): E(V-12) is not linear and there is a more rapid increase of E(V-L) in the region of large E(V-12) values. The same conclusion follows from the consideration of the E(V-L): E(V-25) and E(V-L): E(V-60)dependencies. In contrast, the relations between the excesses at 12 $\mu $m, 25 $\mu $m and 60 $\mu $m are quite linear with correlation coefficients $r\approx0.8\ {\rm to}\ 0.9$.

On the one hand, the behaviour can be due to the fact that CS envelopes are optically thin at 3.5 $\mu $m but optically thick at $\lambda>12~\mu$m (Gehrz et al. 1974). This may lead to the behaviour indicated for E(V-L): $E(V-m_{\lambda }$) dependencies. The theoretical interpretation of these dependencies is beyond the purpose of our paper note, however, that a similar behaviour was discussed theoretically by Dougherty et al. (1994). The regions of large E(V-L) and E(V-12) values in Fig. 11 are occupied mainly by early type stars (see Fig. 2a and Coté & Waters 1987). These hotter stars can ionize larger volumes of CS matter, leading to the increase in E(V-L)excesses). Poeckert & Marborough (1982) noted that the dramatic change in ionization structure of CS envelopes is obvious around $T_{\rm e}\approx15\,000\ {\rm to}\ 20\,000$ K corresponding to spectral types B4-B6. At the same time the effective surface area of the emitting regions which are responsible for the excess E(V-12) for B0-B5 stars does not change strongly (see previous section). On the other hand, it is possible to suggest the presence of an additional component to CS envelopes for early spectral type objects close to the star which may be responsible for an increase of near IR excesses. The absence of this second component in late type stars leads to the increase of correlation coefficients for E(V-L): E(V-12) dependence from B2 to B9 stars.

  \begin{figure}
\par\includegraphics[width=7.1cm,height=6.7cm,clip]{9470f12a.ps}\...
...e*{2mm}
\includegraphics[width=7.1cm,height=6.7cm,clip]{9470f12b.ps}\end{figure} Figure 12: Correlation between near a) and far b) IR excesses with $v\sin{i}$values for the entire sample of Be stars
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  \begin{figure}
\par\includegraphics[width=7.2cm,height=6.6cm,clip]{9470f13a.ps}\...
...e*{2mm}
\includegraphics[width=7.2cm,height=6.6cm,clip]{9470f13b.ps}\end{figure} Figure 13: Correlation between near a) and far b) IR excesses with the ratio of $v\sin{i}/v_{\rm c}$ for the entire sample of Be stars
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Another important negative result is the absence of any correlation between near-far IR excesses and $\,v\sin{i}\,$ for 220 and 118 Be stars respectively (see Figs. 12a,b) (and for any spectral subgroup considered separately). This behaviour may result from the small optical depth of CS environment for the majority of Be stars in the near IR. Another possibility to account for this behaviour is a suggestion of either a more spherical geometry for the CS environment where the near IR emission arises or the presence of two independent regions - a disk component and a spherical component or polar lobes, both responsible for the near IR emission. The suggestion on two distinct regions in CS environment in classical Be stars (a diffuse polar stellar wind and a dense equatorial disk) is discussed currently in literature (see, for example, Porter, 1998 and references therein). Moreover, in context of polarization modeling, Fox (1991) supposed that for some Be stars the polar region can be the dominant source of free electrons. To minimize the uncertainties due to mixing in a same diagram involving stars with different masses and luminosity classes, we re-construct Fig. 12 using the ratio $v\sin{i}/v_{\rm c}$ instead of the values of $v\sin{i}$. However, as follows from Fig. 13, no correlations appear even with this adjustment. As was noted above, however, CS envelopes are optically thick at 12 $\mu $m. In the framework of this assumption, strongly flattened disks would produce high colour excesses for the case of pole-on orientation and significantly lower excesses at high inclinations (edge-on). For the geometrically thick disks (with $\Theta >50\hbox{$^\circ$ }$) we would expect an opposite behaviour, namely high excesses at $i=90\hbox{$^\circ$ }$ and lower excesses at $i=0\hbox{$^\circ$ }$. The absence of correlations between E(V-12) and $v\sin{i}$ indicates that the effective surface area of emitting regions is approximately equal for pole-on ( $S_{1}(i=0\hbox{$^\circ$ })\simeq \pi R^2$) and edge-on ( $S_{2}(i=90\hbox{$^\circ$ })\simeq 2\pi R^2\tan\Theta$) cases, where R is the radius of the disk and $\Theta$ is its half-opening angle. Regarding the disk-like structure, from simple geometrical considerations, this is realized for disks with a half-opening angle $\Theta\approx25\hbox{$^\circ$ }$. Such behaviour can never be obtained for ellipsoidal envelopes as the effective surface area (and thus E(V-12)) would be always larger for a pole-on orientation! In addition, note that according to Fox (1991, 1994) optically thin ellipsoidal envelopes are unable to produce polarizations in excess of 1.2%. Thus, the implication of this configuration of CS envelopes is at least questionable. Assuming $\sigma_{E(V-12)}\approx0\mbox{$\,.\!\!\!^{\rm m}$ }2$, for the difference in E(V-12) not to be detectable at 3$\sigma$ level, the ratio of the effective surface areas for pole-on and edge-on disks cannot exceed 0.6. With this ratio the range of the half-opening angle of CS disks is $10\hbox{$^\circ$ }<\Theta<40\hbox{$^\circ$ }$. Waters (1986) showed that for a disk with $\Theta=10\hbox{$^\circ$ }$, the effect of inclination on the excess flux cannot be negligible for $i>50\hbox{$^\circ$ }$. Our estimate of $\Theta$ is in agreement with that of Waters (1986) and Hanuschik (1996) but it clearly contradicts theoretical predictions for WCD models of Bjorkman & Cassinelli (1993) and Owocki et al. (1994). De Araújo et al. (1994) have determined the angle of a CS envelope where the density has decreased by a factor of 1/e with respect to the equatorial value as about $17\hbox{$.\!\!^\circ$ }5$ which is also in agreement with our data. Our large statistical sample allows us to suggest that any uncertainties due to non-simultaneous observations and/or variability of observed parameters should not affect the results significantly and the lack of any strong correlations is a real outcome.

However, if all Be stars are surrounded by CS disks, correlations might be expected between the intrinsic polarization and projected rotational velocities. This dependence was first investigated by McLean & Brown (1978) and recently for a larger sample of stars by Yudin (2000). In both cases, the relation between $p_{\ast }$ and $v\sin{i}$ shows a triangular distribution but with very different boundaries. According to McLean & Brown (1978), the polarization exhibits a maximum scatter for the largest values of $v\sin{i}$. In contrast, Yudin (2000) found that $\,p_{\ast}\,$ reaches maximum values for stars with projected rotational velocities in the intermediate range of 150 kms-1 $< v\sin{i} < 250$ kms-1 (Feature 1) and there are none (with a few exceptions) with large polarization among the stars with relatively low $v\sin{i}$ (<100 kms-1), (Feature 2) and very high $v\sin{i}$ (>300 kms-1), (Feature 3). Note that Yudin (2000) used the data of intrinsic polarization for about 90 objects and his result is well confirmed in the present study for the largest list of intrinsic polarization of classical Be stars currently available (337 objects, see Fig. 14). The distribution constructed here has a peak at the value $v\sin{i}\approx 200$ kms-1 and the boundary lines are described by:

$p_{\ast}(\%) = 0.01(v\sin{i})$ for $0<v\sin{i}<200$ kms-1and

$p_{\ast}(\%) = 4-0.01(v\sin{i})$ for $200<v\sin{i}<400$ kms-1. The behaviour corresponding to Feature 2 has already been discussed in terms of high inclinations of the envelope symmetry axis to the line of sight (McLean & Brown 1978). While the polarization by scattering in any optically thin axisymmetric CS envelope is proportional to the optical depth and $\sin^{2}{i}$, the increased scatter in the $p_{\ast }$: $v\sin{i}$ diagram would be observed toward the larger values of $v\sin{i}$ (Feature 1). However, polarization of about 2% is the limit in the canonical model adopted for Be stars which is well confirmed in our study. Fox (1991), however, showed theoretically that the inclination dependence is more complicated than in the model of Brown & McLean (1977) and that the expression $p_{\ast}\propto\sin^2{i}$ no longer holds. Again, to minimize any uncertainties due to mixing of stars with different stellar masses and luminosity classes, we re-construct Fig. 14 using the ratio $v\sin{i}/v_{\rm c}$ instead of the values of $v\sin{i}$. The same triangular shaped distribution is apparent in Fig. 15. The peak of the distribution is at the value $v\sin{i}/v_{\rm c}=0.41$, corresponding to the value $v_{\rm t}/v_{\rm c}\approx0.52$. The boundary lines are described as follows:

$p_{\ast}(\%) = 4.88(v\sin{i}/v_{\rm c})$ for $0<(v\sin{i}/v_{\rm c})<0.4$ and

$p_{\ast}(\%) = 3.39-3.39(v\sin{i}/v_{\rm c})$ for $0.4<(v\sin{i}/v_{\rm c})<1$.

Finally, note that less than 3% of Be stars are located outside of the triangular distribution.

Let us consider now a few hypothesis in context to Feature 3. First, to account for this behaviour, it must be remembered that a rapidly rotating Be star (with the value of $v\sin{i}\approx 300$-400 kms-1) is at the stability limit and has a large coefficient of non-sphericity.

  \begin{figure}
\par\includegraphics[width=7.2cm,height=6.6cm,clip]{9470f14.ps}\end{figure} Figure 14: Correlation between $p_{\ast }$ and projected rotational velocities for the entire sample of classical Be stars
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  \begin{figure}
\par\includegraphics[width=7.2cm,height=6.6cm,clip]{9470f15.ps}\end{figure} Figure 15: Correlation between $p_{\ast }$ and the ratio of $v\sin{i}/v_{\rm c}$ for the entire sample of classical Be stars
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It is well known that the rapid rotation of the star produces two effects, namely flattening of the star at the poles and, secondly, a gravitationally induced darkening of the equatorial region. Both of these effects contribute to a polarization whose direction is perpendicular to the polar axis i.e., orthogonal to the vector of polarization arising in an optically thin CS gaseous disk (Bjorkman & Bjorkman 1994). Consequently, the observed polarization, being the vector sum of the two components (CS polarization and star's photospheric polarization), tends to diminish toward the highest $v\sin{i}$ values, beginning at some limiting value, this leading to the appearance of the "triangular" distribution of $p_{\ast }$: $v\sin{i}$. Note however, that the depolarizing effect is small, ( $\Delta p_{\ast}<0.3\%$, see Bjorkman & Bjorkman 1994), especially taking into account that the decrease of $\,p_{\ast}\,$ is clearly obvious from the relatively small value $v_{\rm t}/v_{\rm c}\approx0.6$ (see further discussion). Moreover, scattering of stellar polarized radiation in a CS envelope would lead to appearance of circular polarization (also true for multiple scattering) but this is not detected in Be stars at the moment.

The second possibility to account for the above mentioned behaviour is that the triangular shaped distribution might be the result of a combination of two facts established above namely: larger mean projected rotational velocities and smaller absolute values of polarization for late spectral type stars. In this case, most late spectral type stars will be located at the lower right side of the diagram that tending to the decrease of polarization toward larger values of $v\sin{i}$ for the sample of Be stars. However, a similar diagram constructed with just B6-B9.5 stars again shows the same behaviour with a triangular distribution - as well as for the other spectral subgroups of Be stars treated separately. Therefore, the common behaviour is attributed to rapid rotation independently on spectral subtypes.

An alternative suggestion is that the stars with a rapid rotation may form narrower CS gaseous disks. Because the generated polarization is proportional to the ratio of thickness to length of the disk (or to an opening angle, see, for example, Dolginov et al. 1995), such narrower disks produce a significantly lower level of polarization due to increased dilution by unpolarized starlight. Inasmuch as we exclude from consideration multiple scattering, ellipsoidal envelopes, geometrically thick and strongly flattened disks, let us discuss now the optically thin CS disks with $10\hbox{$^\circ$ }<\Theta<40\hbox{$^\circ$ }$. For disk-like envelopes the maximum degree of polarization ( $p_{\ast}\approx1.5$-$2\%$ for the optical depth $\tau\approx0.5$) occurs at $\Theta\approx35\hbox{$^\circ$ }$ (Waters & Malborough 1992; Fox 1993a, - for single-scattering, plus attenuation) that is similar to the above derived upper limit of $\Theta$. As follows from the theoretical calculations of Fox (1993b, 1994) and Waters & Malborough (1992), a decrease of $\Theta$ from $35\hbox{$^\circ$ }$ to $10\hbox{$^\circ$ }$ leads to the decreasing in polarization from 1.5-2% to 0.5-0.7%. In addition, the above mentioned authors showed that polarization reaches a maximum at the inclination angle $i\sim85\hbox{$^\circ$ }$ rather than at $i\sim90\hbox{$^\circ$ }$. Thus, for exactly edge-on orientation of CS envelopes the observed polarization is reduced by about 0.3-0.5%. Taking into account the star's non-sphericity, a combination of these three effects can reduce the intrinsic polarization to zero for stars with rapid rotation, viewed edge-on. Although the models of disk formation around early-type stars currently discussed in the literature (rotation induced bi-stability and wind compressed disks) cannot explain the existence of CS disks with $\Theta>5\hbox{$^\circ$ }$, in both models the opening angle of a disk decreases with the increase of the ratio $\overline{v_{\rm t}}/v_{\rm c}$.

An interesting point is that the peak in the distribution $p_{\ast }$: $v\sin{i}/v_{\rm c}$ is different for our spectral subgroups (see Table 8). In the framework of the above suggestion, the compression of CS disks which affects the depolarization, sets in for lower values of $\overline{v_{\rm t}}/v_{\rm c}$ for early type stars. However, this hypothesis requires a more detailed theoretical study.

 

 
Table 8: Location of the peaks in $p_{\ast }$: $v\sin{i}/v_{\rm c}$, $p_{\ast }$: $v_{\rm t}/v_{\rm c}$ distributions and the average values of $\overline{v\sin{i}}/\overline{v_{\rm c}}$, $\overline{v_{\rm t}}/\overline{v_{\rm c}}$for different spectral subgroups of Be stars

O-B1 B2 B3-B5 B6-B9 O-B9
$(v\sin{i}/\overline{v_{\rm c}})_{\rm peak}$ 0.33 0.41 0.47 0.56 0.41
$\overline{v\sin{i}}/v_{\rm c}$ 0.40 0.45 0.56 0.62 0.50
$(v_{\rm t}/\overline{v_{\rm c}})_{\rm peak}$ 0.42 0.52 0.60 0.71 0.52
$\overline{v_{\rm t}}/v_{\rm c}$ 0.51 0.57 0.72 0.80 0.64


Finally, note that our study is essentially just one of statistical analysis only of some of the observational characteristics of Be stars and most physical explanations are only a simple sketch. To construct a self-consistent model of Be phenomena, a detailed theoretical interpretation of the new results presented here and earlier results well confirmed in the present study now needs to be undertaken.

9 Conclusions

A statistical analysis of some observational characteristics (polarization, projected rotational velocities and near-far IR excesses) for the largest currently available list of classical Be stars (627 objects) has been completed. Our main conclusions may be summarized as follows:

1.
Polarization and near IR excesses of Be stars plotted against spectral types show the same behaviour, namely a maximum mean value for B1-B2 spectral types with a decrease toward late spectral types;
2.
Projected rotational velocities for the different spectral subgroups of Be stars are statistically significantly different. We confirmed that for luminosity class V, late spectral type stars rotate faster on average and the ratio of $\overline{v\sin{i}}/v_{\rm c}$ for them is larger than for early spectral types. For the III-IV luminosity classes, no significant differences exist between $\overline{v\sin{i}}$ but the ratio of $\overline{v\sin{i}}/v_{\rm c}$ is also larger for late spectral type subgroups. All the above confirm well the results of previous studies;
3.
Analysis of the data allows us to conclude that for E(V-L) excesses, there is a bi-modal distribution for O-B1.5, B2-B2.5 and B3-B5.5 spectral subgroups. Such a behaviour does not appear for late spectral types (B6-B9.5). The second peak in E(V-L) distributions transits to the lower values from early to late spectral type subgroups;
4.
We conclude that about 95% of Be stars exhibit intrinsic polarization on the level $0\% < p_{\ast} < 1.5\%$;
5.
No correlation is found between $p_{\ast }$ and E(V-L). In contrast, a clear relation between $p_{\ast }$ and far IR excesses at 12 $\mu $m is confirmed;
6.
No correlation is observed between E(V-L), E(V-12) and $\overline{v\sin{i}}$ or $\overline{v\sin{i}}/v_{\rm c}$;
7.
A clear relation between the intrinsic polarization and $v\sin{i}$(as well as for $p_{\ast }$- $\overline{v\sin{i}}/v_{\rm c}$) is found in the form of "triangular distribution'' with a decrease of $p_{\ast }$ toward very small and very large $v\sin{i}$ (and $\overline{v\sin{i}}/v_{\rm c}$) values. The peak of this distribution is at values $\overline{v\sin{i}}\approx200{-}220$ kms-1 and $\overline{v\sin{i}}/v_{\rm c}\approx0.41$( $\equiv\overline{v_{\rm t}}/v_{\rm c}\approx0.52$). The decrease of intrinsic polarization toward larger values of projected rotational velocities can be understood in the context of the larger oblateness of CS disks for the stars with a rapid rotation;
8.
From the analysis of correlations between different observational parameters we conclude that circumstellar envelopes for the majority of Be stars are optically thin disks with the range of the half-opening angle of $10\hbox{$^\circ$ }<\Theta<40\hbox{$^\circ$ }$ and the opening angle of CS disks may be smaller for late type stars.

Acknowledgements
I wish to express my sincere thanks to Dr. D. Clarke (Glasgow University) for useful discussions and for the help in the improving of the text. I also thank the referee (Dr. J. Zorec) for his helpful comments. We acknowledge the use of the SIMBAD database and this research has made use of the VizieR Service at Centre de Données Astronomiques de Strasbourg. The research described in this paper was made possible in part by the 99-02-16336 grant of RFBR.

References

 

Online Material


Appendix I. Observational data of classical Be stars

HD
HR MWC Sp E(V-L) $p_{\rm intr}$ $\overline{v\sin{i}}$ E(V-12) other name remarks

144
7 2 B9IIIe 0.05 0.30 $146\pm14$   10 Cas  
4180 193 8 B2Ve 0.87 0.23 $221\pm~9$ 1.48 22 Cas,o Cas  
5394 264 9 B0IVe+sh 1.76 0.43 $253\pm24$ 2.13 $\gamma$ Cas  
6811 335 420 B6.5IIIe 0.15 0.14 $~88\pm13$ 0.44 $\phi$ And  
7636   12 B2IIIne $\approx$0.5 0.51 $148\pm~3$ 1.86 V764 Cas  
9709   426 B8V     $297\pm30$      
10144 472   B3Vep 0.20 0 $207\pm~9$ -0.05 $\alpha$ Eri  
10516 496 16 B0.5IVe+sh 1.80 2.17 $395\pm29$ 2.36 $\phi$ Per  
11415 542   B3V 0.12 0.28 $~38\pm~9$   $\varepsilon$ Cas  
12302   23 B1Vep 0.55 0.80 $208\pm24$   V780 Cas  
12856   25 B0pe   0.91 $163\pm~9$      
13051   27 B1IVe 1.72 0.92 $157\pm~7$   V351 Per  
13429   439 B3V     $255\pm26$      
13661   29 B2Ve 0.5   $196\pm21$   V594 Per  
13669   707 B2Vne     $304\pm22$      
13758     B1V   1.48 $202\pm20$      
13867   442 B5Ve     $~93\pm16$      
13890   443 B1IIIe   0.95 $179\pm~8$      
14422   37 B1Vpe 0.16 0.47 $~98\pm10$   V424 Per  
14605   44 B1IVpe 0.70 0.47 $150\pm~3$   V361 Per  
14850     B7III/IVe     $200\pm20$      
15238   47 B3V $\approx$0.15   $273\pm27$   V529 Cas  
15450   48 B1IIIe   0.97 $242\pm24$   V555 Per  
18552 894 455 B8Vne $\approx$0.2 0.38 $260\pm12$      
18877   721 B9Ve   0.45 $178\pm~1$      
19243     B1Ve   0.78 $138\pm14$ 1.91    
20017     B7Ve   0.62 $249\pm46$      
20134   64 B2.5Vep   0.90 $~87\pm~9$      
20336 985 65 B2.5Ven 0.80 0.65 $286\pm19$ 0.86 BK Cam  
20340   723 B3Ve     $250\pm25$      
20418 989   B5V   0.13 $262\pm~4$   31 Per  
20899   725 B9e     $162\pm14$      
21212   67 B1e 1.82 2 $106\pm18$ 1.89    
21362 1037   B6Vn   0.1 $313\pm21$      
21455 1047   B7V   0.10 $138\pm~3$ 1.02    
21551 1051   B7V 0 0.85 $296\pm~8$      
21641   727 B8.5Ve   0.26 $170\pm~1$      
21650   68 B6Ve   0.6 $226\pm22$      
22192 1087 69 B4.5Ve+sh 0.58 1.7 $297\pm41$ 1.84 $\psi$ Per,37 Per  
22298   70 B2Vne   1.12 $154\pm15$ 1.25 CT Cam  
22780 1113 463 B7Vne 0.38 0.47 $283\pm~8$      
23016 1126   B8.5Vne 0.04 0.55 $278\pm14$   13 Tau  
23302 1142 72 B6IIIe 0.13 0.09 $189\pm~7$ 1.25 17 Tau  
23478     B3IVe:   1.3 $170\pm~7$      
23480 1156 73 B6.5IVe 0.55 0.18 $252\pm28$ 0.57 23 Tau,V971 Tau  
23552 1160 464 B8Vne $\approx$-0.15 0.16 $218\pm~3$ 0.73    
23630 1165 74 B7IIIe 0.19 0.12 $173\pm25$ 0.60 $\eta$ Tau,25 Tau  
23800     B1.5IVe   1.26 $178\pm~5$      
23862 1180 75 B8Vpe+sh 0.58 0.38 $295\pm15$ 1.02 28 Tau  
23982   76 B4e     $173\pm~5$ 1.83    
24479 1204 77 B9.5Ve $\approx$0.2 0.21 $110\pm~9$ -0.04    
24534 1209   O9.5Vep 0.50 0.48 $162\pm23$ 0.89 X Per  
25348   80 B1Vpnne   1.16 $202\pm20$   DE Cam  
25799     B3V   0.45 $322\pm32$   V490 Per  
25940 1273 81 B4Ve 0.57 0.17 $198\pm31$ 1.53 48 Per,MX Per  
26356 1289   B5Ve   0.06 $274\pm24$ 1.07    
26398   468 B7III     $167\pm~2$ 1.57    
26420   82 B3Ve   0.66 $186\pm29$      
26670 1305   B6V $\approx$1.1   $263\pm26$      
26906   83 B2Ve   1.22 $230\pm11$   V586 Per  
27846     B1.5V     $134\pm15$      
28497 1423 86 B1Ve 1.21 1.02 $256\pm38$ 2.26 DU Eri Vega-type?
29441   733 B2.5Vne     $311\pm40$   V1150 Tau  
29866 1500 88 B7.5IVne 0.28 1.19 $250\pm11$ 0.80    
30076 1508 89 B2Ve 0.84 0.17 $213\pm25$ 1.04 DX Eri,56 Eri  
30123   736 B8IIIe     $~90\pm~1$      
32190     B1Ve   0.08 $130\pm13$   V1153 Tau  
32343 1622 96 B3Ve 0.99 0.12 $118\pm11$ 2.06 11 Cam,BV Cam  
32990 1659   B2Ve 0.50 0.69 $~94\pm~2$   103 Tau  
32991 1660 98 B3Ve 0.80 0.40 $198\pm~2$ 1.88 105 Tau,V1155 Tau  
33152   99 B1Ve   0.75 $~98\pm10$   V412 Aur  
33232   100 B2Vne 0.75 0.92 $214\pm44$      
33328 1679   B2IVne 0.26 0.24 $271\pm26$   $\lambda$ Eri  
33461   101 B2Vnne 1.85 0.64 $145\pm61$ 1.93 V415 Aur  
33599     B5pe   0.7        
33604   103 B2Ve   0.44 $134\pm20$      
33988   104 B0Ve   0.22 $134\pm41$   12 Aur  
34257   489 B5/8e     $218\pm20$      
34921   107 B0IVpe 1.52 2 $234\pm~4$ 1.94    
34959 1761   B5Vpn   0.7 $233\pm45$   V1369 Ori  
35165 1772   B5IVe+sh 0.12 0.7 $272\pm27$      
35345   109 B1.5Vpe   0.65 $110\pm11$      
35347   494 B1Ve   1.11$^\dagger$        
35411 1788   B1V+B2V 0.15 0.20 $~58\pm~2$ 0.15 $\eta$ Ori  
35439 1789 110 B1Vpe 0.47 0.46 $266\pm23$ 2.06 25 Ori, V1086 Ori  
36012   757 B4Ve   0.10 $162\pm~3$   V1372 Ori  
36376   760 B3/8e     $~58\pm~4$   V1374 Ori  
36408 1847   B7IIIe     $~66\pm~6$ 0.54    
36576 1858 111 B1.5IVe 0.58 1.17 $231\pm13$ 2.00 120 Tau  
36665   501 B0/8e     $194\pm~1$      
37115   114 B6Ve 0.86 0.37 $226\pm23$     Vega-type?
37202 1910 115 B1IVe+sh 0.96 1.13 $241\pm27$ 1.83 123 Tau,$\zeta$ Tau  
37330   116 B6V   0.26 $134\pm~7$      
37490 1934 117 B3IIIe 1.02 0.27 $171\pm18$ 1.07 $\omega$ Ori,47 Ori  
37541   769 B5e     $154\pm12$      
37657   118 B3Ve   1.32 $216\pm20$   V434 Aur  
37795 1956 119 B7.5Ve 0.28 0.15 $184\pm~5$ 0.86 $\alpha$ Col  
37967 1961   B2.5Ve $\approx$0.5 1.1   1.76 V731 Tau  
38010   124 B1Vpe   0.33 $338\pm~3$ 2.21 V1165 Tau  
38087     B5Ve 0.49 2.5   3.79    
38191   125 B1Vne   0.5        
38708     B3Ve $\approx$0.25 1.06 $226\pm~4$   V438 Aur  
39018   779 B9e     $194\pm14$      
39340     B3Ve   0.13 $222\pm22$      
39478   129 B2Ve   2        


Appendix I. Observational data of classical Be stars

HD
HR MWC Sp E(V-L) $p_{\rm intr}$ $\overline{v\sin{i}}$ E(V-12) other name remarks

40193
    B8Vne   0.4        
40978   131 B3Ve   0.58 $202\pm~3$   V447 Aur  
41335 2142 133 B2Vne 1.57 0.60 $352\pm60$ 2.23 V696 Mon  
42054 2170 134 B4IVnne   0 $220\pm22$ 1.72   Vega-type?
42529   794 B9e     $242\pm13$      
42545 2198   B5Vne $\approx$0 0.1 $273\pm23$   69 Ori  
43285 2231 136 B5.5Ve 0 0.08 $260\pm12$      
43544 2249   B2.5Ven 0.13 0.05 $303\pm~4$      
43703   799 B1IVe   1.3 $216\pm~2$      
44458 2284 138 B1Ve+sh 1.40 0.72 $224\pm21$ 2.24 FR CMa  
44506 2288   B3Ve+sh   0.39 $218\pm40$      
44637   139 B2Vpe   0.6 $130\pm13$      
44996 2309 526 B2.5Ve 0.12   $~98\pm33$      
45314   140 B0IVpe 0.63 0.2 $245\pm25$      
45542 2343 141 B6IIIe+sh 0.07 0.10 $193\pm14$ 0.54 18 Gem,$\nu$ Gem  
45626     B7pe 0.5 1.25        
45725 2356 143 B3Ve+sh 1.04 0.24 $308\pm27$ 2.25 $\beta$ Mon A,11 Mon  
45726 2357   B3Vpe   0.13 $295\pm30$   $\beta$ Mon B  
45871 2364   B5Ve $\approx$0.4   $307\pm44$      
45910   145 B2IIIpe+sh 1.85 0.70 $205\pm155$ 2.23 AX Mon  
45995 2370 146 B2Vne 1.20 0.91 $254\pm~5$ 2.28    
46380   530 B1Ve $\approx$0.45 1.28 $262\pm12$   V728 Mon  
46680     B9IV     $200\pm20$   $\mu $ Pic  
47054 2418 150 B8Ve $\approx$0.6 0.34 $226\pm20$ 0.83    
47359     B0.5Vp   0.7        
47761   531 B1Ve   0.6 $~82\pm~5$   V733 Mon  
48282     B3III   1.0        
48917 2492 152 B2Ve 0.95 0.51 $200\pm20$ 1.80 10 CMa,FT CMa Vega-type?
49131 2501   B2IIIe     $295\pm30$ 2.09 HP CMa Vega-type?
49330   821 B0pnne   1.14     V739 Mon  
49336 2510   B4Vne   1.65     V339 Pup Vega-type?
49787   153 B2Ve   0.7 $186\pm~2$      
49888   534 B3Ve   0.50 $250\pm~2$      
49977   154 B2Ve $\approx$0.5 1.95 $218\pm~4$   KU CMa  
50013 2538 155 B1.5IVne 1.84 0.3 $201\pm24$ 2.71 $\kappa$ CMa  
50083   156 B2Ve   1.25 $178\pm~2$ 2.27 V742 Mon  
50123 2545 157 B6IVe 1.42   $226\pm~5$ 1.84   Vega-type?
50658 2568 537 B8IIIe 0.19 0.6 $234\pm~5$   19 Aur  
50696     B1Vnne   0.6        
50820 2577 827 B3IVe 1.52   $119\pm12$ 1.41    
50938   540 B3Ve     $162\pm~5$   LL CMa  
51354   160 B3Ve   1.0 $306\pm25$      
51480   161 B8e 1.53 0.55   1.97 V644 Mon young?
52244   163 B2IIIpne   1.33     LP CMa  
52356     B4Ve     $394\pm58$   LQ CMa  
52437 2628   B2Vne   0.12 $178\pm18$   FU CMa  
52721     B2Ve 0.71 1.4 $243\pm93$ 2.79 GU CMa  
52812     B3V   1.05        
52918 2648   B1Ve 0.35 0.4 $280\pm~7$ 1.42 19 Mon  
53257 2659   B9IV $\approx$0.4   $304\pm~5$   44 Gem  
53367   166 B0IVe 1.25 0.75 $~86\pm20$ 2.53 V750 Mon  
53416     B8e     $194\pm~2$      
54309 2690 167 B1.5IVe 1.14 0.55 $210\pm30$ 1.76 FV CMa  
54464   836 B2.5Ve   0 $154\pm~1$      
54475 2691   B2V     $200\pm20$      
54786     B0pe   1        
55135   168 B4Vne   0.30 $258\pm25$      
55538     B2Ve   0.65 $146\pm11$   HI CMa  
55606     B1Vpnne   0.55        
56014 2745 170 B3IIIp+sh 0.33 0.25 $144\pm~5$ 1.11 27 CMa,EW CMa  
56139 2749 171 B2.5Ve 0.92 0.14 $109\pm~8$ 1.15 $\omega$ CMa,28 CMa  
56806     B1.5Vpnne   0.3        
57150 2787 173 B2Ve 1.04 0.77 $254\pm35$ 1.98 NV Pup Vega-type?
57219 2790   B2Vne 0.10 0.03 $117\pm16$ 0.26 NW Pup  
57386   174 B2Ve   0.18 $274\pm15$      
57393   556 B2Vnne   0.6        
57539     B5III   0.5        
58011     B1Vnep   0.1 $~18\pm~2$      
58050 2817 176 B2Ve 0.69 1.12 $123\pm~6$   OT Gem  
58127     B6e     $234\pm10$      
58155 2819   B3V     $250\pm25$      
58343 2825 177 B3Ve 0.86 0.40 $~57\pm15$ 1.64 FW CMa  
58715 2845 178 B8Ve 0.24 0.14 $244\pm~6$ 0.60 $\beta$ CMi,3 CMi  
58978 2855 179 B0.5IVne+sh 1.10 0.85 $245\pm32$ 1.88 FY CMa  
59094   561 B1Ve 1.18 0.18 $218\pm18$   V370 Pup  
59498     B2Vne   0.12        
60307     B3.5IIIe     $220\pm22$      
60606 2911 183 B3Vne 1.21   $270\pm39$ 2.17 OW Pup,Z Pup  
60757   848 B5e     $170\pm~3$   V763 Mon  
60848   184 O8Vpe 1.20 0.22 $247\pm31$   BN Gem  
60855 2921 565 B2Ve 0.14 0.31 $239\pm~6$ 1.03    
61224 2932   B9IIIe     $234\pm~2$      
61355     B3Vep   0.8        
61925 2968   B5IV     $200\pm20$      
62367   567 B8e     $114\pm~6$      
62532     B1Vpnne   0.55        
62654     B3Vne   0.7        
62729   572 B3Ve     $194\pm~5$      
62753   185 B2.5Vne   0.65     V387 Pup  
62780   573 B2IIIne   1.90        
63150     B0.5IVnep   1.5        
63359     B1Vpe   0.9        
63462 3034 186 B1IVe 1.21 0.2 $323\pm12$ 1.71 o Pup  
64109   187 B8e     $250\pm41$      
64298     B2IVnne   0.68        
65663     B8V $\approx$0.30          
65719     B2.5IIIe   0.15     V408 Pup  
65875 3135 190 B2.5Ve 1.08 0.15 $153\pm19$ 1.82 V695 Mon  
66194 3147   B2.5Ve 0.24 0.32 $224\pm24$ 0.67 V374 Car Vega-type?
68468   577 B4e $\approx$0.5   $122\pm~8$      
68980 3237 192 B1.5Ve 0.79   $127\pm12$ 1.97 r Pup,MX Pup  
69168     B3V   0.16        
69404   193 B2Vne   0.4 $298\pm30$      
69425     B1Vne   1.11        
71072   857 B3.5IVe $\approx$0   $202\pm~2$      


Appendix I. Observational data of classical Be stars

HD
HR MWC Sp E(V-L) $p_{\rm intr}$ $\overline{v\sin{i}}$ E(V-12) other name remarks

71510
3330   B2Ve 0.06   $162\pm18$      
71934     B2IVne   0.46        
72014     B1Vnne   0.65 $221\pm~8$      
72063   858 B2Vne   0.9        
72067 3356   B2Ven   0.2 $150\pm15$ 1.54    
74401     B1.5IIIne   1.3        
75081 3488   B9Ve     $223\pm22$      
75311 3498 195 B3Vne 0.18   $269\pm24$ 0.65 V344 Car  
75658     B1IVe   0.45        
76534     B2V 0.29 0.53 $202\pm20$   OU Vel  
77032     B2Vne   1.14        
77320 3593   B2.5Ve 0.83 1.24 $284\pm38$   IU Vel  
78764 3642 196 B2IVe   0.08 $127\pm~6$   V345 Car  
79351 3659   B2.5V     $~35\pm~5$   a Car  
79621 3670   B9V     $170\pm17$      
79778     B2IVne   0.2        
80834     B5Vnne   0.73        
81357   859 B8.5e $\approx$1.5   $162\pm16$     binary
81654     B2Ve   0.69        
81753 3745   B5Ve     $300\pm30$     Vega-type?
82830     B1IIIne   2.0        
83043     B2Vpne   0.92 $174\pm17$      
83060     B2Vnep   0.50        
83597     B1.5Ve   1.78        
83953 3858 197 B6Ve 0.46 0.32 $273\pm18$ 1.78 I Hya Vega-type?
84523     B3Ve   0.25        
84567 3878   B0.5IIIne   0.25 $242\pm24$      
86272     B2Vne   0.5        
86612 3946 581 B4Ve 0.82 0.01 $187\pm19$   OY Hya  
86689     B2Vne   0.71        
87380     B1IVn   0.20 $230\pm23$      
87543 3971   B7IVne   0.20   1.44    
87901 3982   B7V 0.12 0.1 $258\pm32$ 0.11 $\alpha$ Leo  
88661 4009 199 B2IVpne 0.97   $262\pm40$ 1.89 QY Car  
89080 4037   B8IIIe+sh 0.34 0.45 $207\pm13$ 0.71 $\omega$ Car  
89884   582 B5IIIe $\approx$0.3   $256\pm33$      
89890 4074 201 B3IIIe     $~70\pm~7$ 0.27    
90187     B1IIIne   0.45        
90563     B2Ve   0.9        
91120 4123 205 B9Vne+sh 0.13 0.23 $265\pm33$   Z Crv,5 Crv  
91188     B4IIIe   1.25        
91465 4140 208 B4Ve+sh 0.98 1.16 $255\pm~5$ 1.64 P Car  
92027     B2.5Vne   0.71        
92061     B1.5IIIe   0.05 $124\pm12$      
92714     B2Ve   1.1        
92938 4196   B4V   0.24 $130\pm~3$   V518 Car  
93030 4199   B0Vp 0.3 0.02 $145\pm~6$   $\theta$ Car  
93237 4206   B5IV   0.25 $~70\pm~7$   DR Cha  
93561     B1IIInne   1.0        
93563 4221   B8.5IIIe+sh     $237\pm37$ 0.91    
93683     B1IVnep   1.8        
94648     B2Ve $\approx$1.55 0.3     FK Car  
96357     B1.5Vne   1.3        
96864     B1.5IVnep   1.4        
98624     B1Vne $\approx$1.3 1.1        
98927     B1IIInne   0.8 $102\pm10$      
99354     B1IIIne   0.84        
100199     B1III   0.5 $187\pm19$      
100324     B2Vne   2 $199\pm20$   KP Mus  
100673 4460   B9Ve     $132\pm~5$ 0.12    
100856     B2IVpe     $175\pm18$   V843 Cen  
100889 4468   B9.5V   0.04 $182\pm~9$ 0.05 $\theta$ Crt,21 Crt  
102742     B3Ve   0.15        
102776 4537   B3Vne     $222\pm12$ 0.13    
105382 4618   B6IIIe 0   $111\pm10$ -0.02 V863 Cen  
105435 4621 219 B2IVne 0.97 0.33 $207\pm46$ 1.91 $\delta$ Cen  
105521 4625   B3IVe   0.38 $159\pm40$   V817 Cen  
105675     B2IVne   1.55        
105753     B2IVne   0.7        
107348 4696 221 B8Vne 0.27 0.04 $229\pm24$   $\zeta$ Crv  
109387 4787 222 B6IIIpe+sh 0.63 0.24 $200\pm15$ 1.73 $\kappa$ Dra,5 Dra  
109857     B8Ve $\approx$0.25     0.96   Vega-type?
110335 4823 223 B6IVe+sh   1.05 $208\pm34$ 1.44 39 Cru,CH Cru  
110432 4830 224 B2Vpe 1.29 1.3 $277\pm56$ 2.13 BZ Cru  
110863     B2IIInep   1.94 $182\pm18$   DQ Cru  
112078 4897   B4Vne   0.07 $283\pm11$ -0.11 $\lambda$ Cru  
112091 4899 225 B5Vne 0.62 0.12 $209\pm18$ 1.57 $\mu^{2}$ Cru  
112999     B6IIIn   0.9        
113120 4930 226 B1.5IIIne 0.93 0.4 $307\pm~4$ 1.82    
113605     B2Vpe   0.7        
113902 4951   B8V   0.04 $261\pm26$      
114200     B1IIIne   0.4        
114800     B2IVne   1.7 $204\pm~3$   V955 Cen  
114981     B4Vne   0.02     V958 Cen Vega-type?
116781     B0IIIne   0.8        
117111     B2Vne   0.6 $186\pm19$      
117357     B0.5IIIne   0.8 $~78\pm~8$      
118246     B3Ve   0.05 $277\pm18$   GP Vir  
120324 5193 229 B2IV-Ve 0.97 0 $159\pm~9$ 0.10 $\mu $ Cen Vega-type?
120991 5223 230 B2IIIep 1.22 0.09 $~78\pm~7$   V767 Cen  
121556     B2IVnep   1.73        
121847 5250   B8Ve+sh -0.12 0.04 $193\pm~7$ -0.11 47 Hya  
122450     B2IIIe   0.66        
122669     B0.5Ve 1.1 0.48        
122691     B1Vnne 1.3 1.2        
124367 5316 231 B4Vne 0.82 0.35 $264\pm36$ 2.07 V795 Cen  
124771 5336   B3V   0.37 $201\pm~8$ 0.61 $\epsilon$ Aps Vega-type?
125159     B2Ve   0.3        
127489     B2Ve   0.46 $186\pm19$   V1010 Cen  
127617     B7III/IVe     $152\pm13$      
127972 5440 232 B1.5Vne+sh 0.19 0.47 $291\pm32$ 0.83 $\eta$ Cen Vega-type?
129954 5500   B2.5Ve   0.67 $180\pm18$   CO Cir  
131492 5551   B3Ve 0.68 0.5 $153\pm38$ 0.49 $\theta$ Cir  
133738     B1.5Ve   0.81 $161\pm~3$      
134401     B2Vne   1.2        

                 


Appendix I. Observational data of classical Be stars

HD
HR MWC Sp E(V-L) $p_{\rm intr}$ $\overline{v\sin{i}}$ E(V-12) other name remarks

134481
5646   B9Ve 0.05   $172\pm~8$ 0.29 $\kappa^{1}$ Lup  
135160 5661 234 B0.5Ve 0.27 0.4 $155\pm19$      
135734 5683   B8Ve     $243\pm92$ 0.62 $\mu $ Lup  
136415 5704   B5IVe+F8   0.36 $273\pm30$   $\gamma$ Cir  
136556     B1Vne   1.45        
137387 5730 235 B3IVpe+sh 1.02 0.45 $299\pm51$ 1.43 $\kappa^{1}$ Aps  
137432 5736   B4Ve $\approx0$ 0.08 $127\pm~7$      
137518     B1IIInep   1.0        
138749 5778 237 B6Vnne 0.17 0.15 $327\pm22$ -0.05 4 CrB,$\theta$ CrB  
138769 5781   B3IV   0.05 $~93\pm16$   KT Lup  
139431     B2Ve     $267\pm32$      
139790     B3IIIne   1.8        
140336     B1IIIne   0.6        
140784 5860   B8Vn   0.1 $357\pm36$      
140926     B2IVne   0.42        
140946     B2IVne   0.5        
141637 5885   B1.5Vn   0.62 $266\pm34$   1 Sco  
141926     B2IIInne   1.05   2.81    
142184 5907   B2Vne 0.20 0.17 $315\pm41$ 0.76    
142237     B3IVne   0.65        
142926 5938 584 B9pe+sh 0.29 0.16 $298\pm27$   4 Her,V839 Her  
142983 5941 239 B3IVe+sh 0.62 0.73 $369\pm22$ 1.64 FX Lib,48 Lib  
144320     B1Vne   0.85 $186\pm19$   V364 Nor  
144708 6002   B9V     $265\pm32$      
144965     B3Ve $\approx$0.5          
144970     B0Ve   1.0 $138\pm14$      
145846     B1.5Vne   0.85 $142\pm27$      
146444     B4Ve   1.25 $268\pm34$      
146463     B2IVnep   1.5        
147274     B7IVe   0.65        
147302     B3Vne   0.35 $369\pm53$      
147756     B1.5Vne   0.1        
148184 6118 241 B1.5Vpe 1.10 0.41 $139\pm14$ 2.18 7 Oph,$\chi$ Oph Vega-type?
148259     B2Ve   0.3 $~86\pm~9$   OZ Nor  
148877     B7Vep   0.25        
149298     B1Ve   1.3 $150\pm15$      
149313     B2IVne   0.39        
149671 6172   B7IVe   0.16 $230\pm23$   $\eta^{1}$ TrA  
149729     B2Vn   0.38 $258\pm26$      
149757 6175   O9Ve 0.50 0.82 $341\pm32$   13 Oph,$\zeta$ Oph  
152060     B2IVe   1.2        
152478 6274   B3Vep+sh 0.78 0.97   2.18    
152541     B7Ve   0.35        
152979     B2IVe   0.1        
153261 6304 245 B2IVe 0.95 0.99 $184\pm~5$ 1.83 V828 Ara Vega-type?
153295   588 B2IIIe   1        
153879   246 B1.5Vne   0.8        
154040   868 B2Ve   1.4 $175\pm18$      
154111     B5Vne   0.4        
154154     B2IVnne 0.80 1.7        
154243   250 B3Vnne   2.0        
154450   251 B0.5IVnne   1.7     V956 Sco  
154911   871 B0.5IVne   0.35        
155438     B6IVn   0.6        
155806 6397 252 O8Ve 1.75 0.30 $116\pm23$     young?
155851   253 B1IIInne $\approx$1.3 1.0        
156325 6422 254 B5Vne 0.06 1.6     V1077 Sco  
156468   255 B1Ve   0.65     V1078 Sco  
157042 6451 258 B2IIIne 1.00 0.44 $318\pm28$ 1.89 $\iota$ Ara  
157832   259 B5Vnne     $277\pm18$ 1.89 V750 Ara  
158319   260 B4Ve   0.9 $234\pm~4$      
158427 6510 261 B2Vne 1.18 0.58 $269\pm13$ 2.23 $\alpha$ Ara  
158643 6519   B9.5V 1.32 0.56 $210\pm31$ 3.70 51 Oph Vega-type
159489     B3IVep   0.35        
160202   264 B7Ve   0.42        
160886   885 B3Vnne   0.34 $328\pm32$   V2243 Oph  
161103     B2IVe   0.95 $260\pm26$      
161261     B9 $\approx$0.07 0.1 $297\pm30$   V2315 Oph  
161543   887 B7.5e     $194\pm~4$   V2385 Oph  
161711     B9III/IVe     $150\pm15$   GT Dra  
161756 6621A   B6Ve $\approx$0.4   $~85\pm30$   V3894 Sgr  
161756 6621B   B8Ve     $154\pm15$   V3894 Sgr  
161774   890 B5Vnne   0.55        
161807     B3Vne   0.35 $287\pm29$ 2.45    
162352   892 B1.5Vne   0.5        
162428   594 B7IV/Ve     $275\pm30$      
162568   893 B3Vne   0.41        
162732 6664   B6IVe+sh 0.4 0.76 $286\pm12$   V744 Her,88 Her  
163454   276 B0.5Vpe   2.57        
163848   899 B8Ve     $269\pm18$      
163868   277 B3.5Vne   0.59 $297\pm29$   V3984 Sgr  
164284 6712 278 B2IV/Ve+sh 0.77 0.52 $220\pm14$ 2.10 66 Oph,V2048 Oph  
164447 6720 279 B8Vne 0.43 0.45 $178\pm37$   V974 Her  
164906   280 B1IV:pe: 1.25 0.55   4.98    
165063     B5Vne   0.35        
165285   281 B1.5Vne   1.5        
165854     B9e     $242\pm10$      
165921     B0Ve 0.41 0.48 $194\pm19$   V3903 Sgr  
166014 6779   B9.5III   0.17 $142\pm18$ 0.20 o Her,103 Her  
166256   283 B9/A0e     $266\pm60$      
166443   596 B1Ve   1.53 $246\pm25$   V4383 Sgr  
166524     B0Vpe   1.09        
166566   284 B1IIIe   0.51        
166596 6804   B2.5IIIp     $207\pm~9$   V692 CrA  
167128 6819   B3IIIep 0.41 0.24 $~66\pm~8$ 1.30 QV Tel  
168135   289 B8Ve     $250\pm20$      
168797 6873 601 B3Ve 0.08 0.18 $251\pm~6$   NW Ser  
168957   292 B4Ve   0.16 $~88\pm12$      
169033 6881 602 B5Ve $\approx$0.10 0.52 $210\pm~7$      
169805   296 B2Ve   0.15 $274\pm~8$      
170061   298 B0.5Vne   0.3        
170235 6929 299 B2IVpe+sh 0.35 0.38 $163\pm16$ 2.22 V4031 Sgr  
170682     B4/5III     $121\pm12$   V3508 Sgr  
170835     B2.5Vne   1.3        


Appendix I. Observational data of classical Be stars

HD
HR MWC Sp E(V-L) $p_{\rm intr}$ $\overline{v\sin{i}}$ E(V-12) other name remarks

171348
  302 B2Vne   0.27     V4400 Sgr  
171406 6971   B4Ve $\approx$0.30 0.28 $264\pm10$   V532 Lyr  
171754   942 B4Ve     $138\pm~2$      
171757   943 B2.5IIIne   0.60 $182\pm18$      
171780 6984 604 B5Vne -0.02 0.16 $256\pm~5$      
172158   946 B7.5Ve   1.08 $232\pm26$      
172252   947 B1Vnpe   0.35 $146\pm15$      
172256   606 B1.5Vne   0.31     V4131 Sgr  
173219   304 B1Vnep   1.83     V447 Sct  
173370 7040   B9Ve 0.17 0.04 $261\pm~9$ 0.56 4 Aql  
173371   956 B9IIIe     $291\pm~4$      
173637   607 B1IVe   1.95 $~98\pm10$      
173948 7074 963 B2II/IIIe+sh   0.50 $177\pm12$   $\lambda$ Pav  
174237 7084 608 B2.5Ve 0.96 0.18 $165\pm~9$ 1.06 CX Dra  
174513   609 B1Ve   1.8 $202\pm~5$   V457 Sct  
174571   610 B3Vpe   1.2 $294\pm19$ 1.92    
174638 7106 306 B7Ve 0.22 0.45 $131\pm19$ 1.14 $\beta$ Lyr  
175863   308 B5Ve   0.8 $170\pm17$      
175869 7158   B8IIIep -0.02 0.46 $120\pm18$   64 Ser  
176159   971 B9e     $218\pm~1$   V1437 Aql  
177015   309 B5Vn   0.87 $236\pm24$      
177291   973 B8Ve 1.44       V4409 Sgr young?
177648   310 B2Ve   0.76        
178175 7249 311 B2Ve 0.73 0.80 $156\pm26$ 1.61 V4024 Sgr  
178475 7262   B5V   0.21 $234\pm20$   $\iota$ Lyr,18 Lyr  
179343   978 B9V+sh 0.15   $261\pm36$      
179405     B3e     $234\pm~1$      
181409 7335   B2IVe $\approx$0 0.30        
181615 7342 313 B2Vpe 3.03 0.68 $~69\pm~7$ 5.66 $\nu$ Sgr HAEBE?
182645 7378   B7III     $250\pm25$      
183362 7403 318 B3Ve+sh 0.73 0.78 $220\pm10$ 1.98 V558 Lyr  
183656 7415 988 B6Ve+sh 0.25 0.54 $216\pm59$   V923 Aql  
183914 7418 618 B8Ve 0.20   $220\pm25$   6 Cyg  
184279   319 B0.5Ve+sh   0.9 $212\pm~9$   V1294 Aql  
184915 7446   B0.5III 0.25 1.17 $229\pm~2$   $\kappa$ Aql  
185037 7457 619 B8Vne 0.66 <0.05 $327\pm18$   11 Cyg  
187350   621 B2IVne   0.85 $199\pm20$      
187567 7554 322 B2.5IVe $\approx$0.6 1.43   2.40 V1339 Aql  
187811 7565 323 B2.5Ve+sh 0.58 0.15 $236\pm21$ 0.67 12 Vul  
187851     B2V   0.71 $234\pm23$   V396 Vul  
189687 7647 624 B3IVe 0.61 0.28 $194\pm13$   25 Cyg,V1746 Cyg  
190944   328 B1.5Vne 1.38 0.97 $162\pm16$ 2.30    
191531   328 B0.5IV     $~80\pm~3$      
191610 7708 329 B3IVe 0.76 0.33 $290\pm31$ 1.60 28 Cyg,V1624 Cyg  
191639 7709   B1Ve 0.18 0.22 $235\pm24$   BE Cap  
192044 7719 331 B7.5Ve 0.21 0.43 $287\pm~5$ 0.89 20 Vul  
192445   332 B2Ve   0.33 $242\pm14$      
192685 7739   B3V 0.15 0.2 $206\pm19$ 1.31 QR Vul  
193009   336 B0Ve   2.1 $220\pm26$   V2113 Cyg  
193182     B7IV/Ve+sh 0.25 0.15 $182\pm18$      
193911 7789 341 B8IIIne+sh 0.11 0.43 $210\pm~6$ 0.90 25 Vul  
194244 7803   B9Ve $\approx$0.1   $221\pm14$      
194335 7807 343 B2IIIne 0.98 0.35 $328\pm23$   V2119 Cyg  
194883   345 B2Ve   1.6     V2120 Cyg  
195325 7836 1019 B9e+sh $\approx$0 0.17 $250\pm36$   1 Del  
195407   346 B0IV:pe 1.51 1.23 $259\pm26$      
195554 7843 637 B9Vne $\approx$0.05   $215\pm21$      
196712 7890 350 B7IIIne $\approx$0.10 0.05 $199\pm19$      
197038     B7e     $194\pm~2$      
197419 7927 1026 B2IV-Ve $\approx$0.15 0.33 $115\pm~6$   V568 Cyg  
197434   1027 B8e     $218\pm~9$      
198183 7963 352 B5Ve -0.02 0.32 $141\pm14$ -0.06 54 Cyg,$\lambda$ Cyg  
198512   354 B1Vnnep   1.8 $178\pm18$   V2135 Cyg  
198625 7983   B4Ve 0.12 0.25 $257\pm~6$ 1.45 V2136 Cyg  
198895   355 B1.5Ve   3.4 $172\pm18$ 1.56 V417 Cep  
198931   1032 B1Ve 1.60 1.92 $322\pm38$      
199218 8009 356 B8Vnne $\approx$0.25 0.24 $288\pm13$      
199356   357 B2IVe 1.1 0.65 $354\pm24$   V2139 Cyg  
200120 8047 359 B1.5Ve+sh 1.05 0.52 $281\pm33$ 2.50 59 Cyg,V832 Cyg  
200310 8053 360 B1Ve 0.14 0.51 $267\pm23$   60 Cyg,V1931 Cyg  
201522     B0Ve   1.0        
201733 8103 363 B4IVp 0.1 1.2 $270\pm27$   V2148 Cyg  
202904 8146 364 B2.5Vne 1.09 0.46 $216\pm20$   66 Cyg  
203025 8153 365 B2IIIe $\approx$0.2 0.63 $130\pm28$      
203064 8154   O7.5IIIe 0.50 0.23 $288\pm~6$   68 Cyg  
203374   366 B0IVpe   1.1 $267\pm~3$ 1.91    
203467 8171 367 B2.5Ve+sh 0.73 0.03 $148\pm~2$ 0.88 6 Cep,V382 Cep  
203699     B3IV   0.18 $114\pm~1$      
203731   369 B1Vne   1.0     V2153 Cyg  
204116     B1Ve   1.18 $170\pm17$   V2155 Cyg  
204185     B2e     $138\pm~3$      
204722   370 B2Ve   1.95 $210\pm21$   V2162 Cyg  
204860     B4Ve   0.2 $226\pm~8$   V2163 Cyg  
205060   371 B6Ve   0.8 $214\pm12$      
205551 8259 641 B9IIIe $\approx$0   $166\pm27$      
205618   642 B1.5Vne   0.95 $299\pm65$   V2166 Cyg  
205637 8260 373 B2.5Ve+sh 0.81 1.20 $269\pm16$ 0.54 $\epsilon$ Cap,39 Cap  
206773   376 B0Vpe 1.6 0.29 $396\pm~6$ 2.33    
207232   377 B7V     $281\pm28$      
208057 8356 644 B3Ve 0.04 0.24 $135\pm12$   16 Peg,OQ Peg  
208220     B1IVe   0.48        
208392   380 B1IIIe   0.34 $258\pm21$   EM Cep  
208682 8375 381 B2.5Ve+sh 1.03 0.70 $269\pm19$ 1.36    
208886     B7III/IVe     $300\pm30$      
209014 8386   B8Ve 0.30 0.15 $350\pm35$ 0.67 $\eta$ PsA  
209409 8402 384 B7IVe+sh 0.13 0.60 $275\pm32$ 0.97 31 Aqr,o Aqr  
209522 8408 650 B4IVne -0.05 0.19 $265\pm27$   UU PsA  
210129 8438 385 B7Vne 0.1 0.32 $201\pm32$   25 Peg  
211835   652 B3Ve     $207\pm15$   V404 Lac  
212044   386 B0Ve $\approx$0.75 0.51 $162\pm~2$ 1.87 V357 Lac  
212076 8520 387 B1.5Vne 0.94 0.12 $121\pm13$   31 Peg,IN Peg  
212571 8539 388 B1Ve+sh 0.34 0.94 $285\pm15$   52 Aqr,$\pi$ Aqr  
212666   1059 B5.5e     $274\pm15$      
212791   653 B6e     $170\pm~3$   V408 Lac  
213088   389 B9e     $202\pm~7$      


Appendix I. Observational data of classical Be stars

HD
HR MWC Sp E(V-L) $p_{\rm intr}$ $\overline{v\sin{i}}$ E(V-12) other name remarks

213129
  654 B5.5e     $194\pm~1$      
214167     B1.5Ve $\approx$0.45 0.2 $295\pm30$   8 Lac A  
214168 8603 390 B2Ve 1.19 0.18 $304\pm11$   8 Lac B  
214748 8628 392 B8Ve -0.03 0.34 $222\pm26$ 0.63 18 PsA,$\epsilon$ PsA Vega-type?
215227   656 B5ne   1.05 $262\pm26$      
215605   658 B2IVnne   1.76        
216057 8682 393 B5Vne $\approx$-0.1 0.39 $283\pm24$      
216200 8690   B3IV:e $\approx$0.45 1.6 $199\pm17$   14 Lac,V360 Lac  
216581     B2.5V     $282\pm28$      
216851   660 B3Vn     $259\pm26$   V423 Lac  
217050 8731 394 B3.5IIIpe+sh 0.72 0.77 $301\pm16$ 2.21 EW Lac  
217061     B1V 0.39 0.43 $226\pm23$      
217543 8758 395 B3.5Vpe $\approx$0.28 0.4 $297\pm17$      
217675 8762   B6IIIpe+sh 0.07 0.13 $258\pm24$   o And,1 And  
217891 8773 396 B5Ve 0.55 0.09 $118\pm14$ 0.51 $\beta$ Psc,4 Psc  
218393   397 B3IVne 1.0 0.33   1.25 KX And  
218674     B3IV/Ve+sh $\approx$0.1 0.36 $234\pm17$   KY And  
219688 8858   B5V -0.01 0.08 $271\pm11$   $\psi^{2}$ Aqr  
220058   398 B1nep   0.1 $422\pm42$   V810 Cas  
220116   399 B1e   1.77 $210\pm~4$   V811 Cas  
223044     B3e     $146\pm~5$      
223387   401 B0Ve   0.9 $202\pm~2$      
224544 9068 406 B6IVe+sh 0 0.79 $155\pm39$      
224559 9070 407 B3.5Vne $\approx$0.15 0.24 $261\pm11$   LQ And  
224686 9076   B8Ve 0.06 0.04 $261\pm14$ 0.22 $\varepsilon$ Tuc Vega-type?
224905     B1Vn   1.15 $258\pm26$      
225095   409 B2IVne $\approx$0.65 0.66 $152\pm10$      
225985   995 B1Vpe $\approx$1.2 0.9        
227836   628 B0/2:V:e $\approx$1.4 1.8$^\dagger$     V425 Cyg  
228104   629 B1IVpe   0.95 $194\pm~3$      
228438   333 B1Ve   0.15 $219\pm22$      
228860     B0.5IVe   1.08        
229171     B0.5IIIn   1.00        
230579   975 B1.5IVne   1.35        
232552    19 B0IVpe   1.09 $151\pm15$      
235668   646 B2e     $247\pm28$   V2172 Cyg  
235795   1057 B1:V:nne   1.2 $195\pm20$      
236689     B1.5Vep $\approx$0.35 0.25 $139\pm14$      
236935    24 B1Vne   1.4 $159\pm16$      
237056   720 B0.5Vpe   0.9 $160\pm17$      
239758   643 B2Vne   1.1 $281\pm28$   V435 Cep  
244894   761 B0.5Ve   1.45 $177\pm18$      
245493   764 B2Vp   0.2 $206\pm21$      
246878     B1Ve   1.1 $137\pm14$      
248753   128 B1Vnne   1.7     V1167 Tau  
249695   785 B1.5Vpnne   0.25        
250028   786 B2Ve $\approx$0.85 1.7        
250163   517 B1Ve   1.8        
250289     B2IIIe   1 $125\pm13$      
254647   798 B0e   0.6        
256577     B2IVp   1.3        
276738   735 B6/7III/V     $220\pm22$      
298298     B1Vpe   0.6        
300584     B1Ve   1.6        
302724     B2Ve   1        
302838     B1Vne   0.4        
305382     B2Ve   1.8        
306209     B1Ve   0.6        
306657     B2Ve     $224\pm22$      
306791     B2IIIe     $154\pm15$      
306793     B3Ve     $208\pm21$      
306797     B5e     $288\pm29$   V855 Cen  
306962     B1IIIne   1.2        
306978     B2Ve     $144\pm14$      
307350     B2IVne   0.5        
312973     B0IVpe   0.9        
316568     B2Vpe   0.8     AS 253  
316587     B1Vne   1        
316589     B2IVe   0.8        
350559     B7IIIe     $186\pm19$      
CD-30 5559     B3Vep   0.7        
CPD-60 3087     B3Ve     $288\pm29$      
CPD-60 3108     B2Vnpe     $208\pm21$      
CPD-60 3122     B3nep     $224\pm22$   V845 Cen  
CPD-60 3125     B2.5Ve     $232\pm23$      
CPD-60 3126     B1.5Vne     $208\pm21$   V846 Cen  
CPD-60 3128     B2.5Ve     $128\pm13$      
CPD-60 3129     B2.5V     $184\pm18$      
CPD-60 3144     B3Ve     $288\pm29$      
CPD-60 4551     B1IIIne   0.71     V959 Cen  
CPD-60 4708     B2Vne   0.38     V696 Cen  
BD-13 2040   180 B7e   0.6        
BD-13 4936   918 B1Vne   1.1        
BD+35 1169   500 B1Vpe   0.9        
BD+41 3731     B2e 0.17 0.85 $252\pm25$      
BD+47 3302     B2Vnep   0.8     AS 458  
BD+49 3735     B1.5Ve   0.4     AS 483,V397 Lac  
BD+53 2964   1067 B2IVpnne   1        
BD+55 589   446 B2IV/Ve     $295\pm30$      
BD+56 473   441 B0.5IIIe $\approx$0.55 1.5 $258\pm26$   V356 Per  
BD+56 484   444 B1IIIe   0.5 $228\pm24$   V502 Per  
BD+56 493     B1Vpe   0.8 $311\pm31$      
BD+56 511     B3III -0.08   $111\pm11$      
BD+56 548   445 B1.5IIIe 1.78   $134\pm14$      
BD+56 573    40 B2III/Ve 1.38   $335\pm34$      
BD+56 579   710 B7IV/Ve     $311\pm31$      
BD+56 582     B1III   1.7 $175\pm18$      
BD+56 624   46 B3IIIe $\approx$0.75 1.5 $234\pm23$      
BD+57 515   28 B2ep   0.65 $218\pm22$      
BD+57 607   55 Be   0.3 $298\pm30$      
BD+58 458   42 B1pe   0.2 $418\pm42$      
BD+59 2829   3 B0IVne   0.3        
BD+61 2355     B7IV 0.36       BHJ 9  
BD+61 2380     B9Ve -0.1          

$\dagger$ - observed polarization;

The columns in the Appendix I give the HD number or other identification, the MK spectral type of a star (as from the source catalogue), the calculated value of colour excess E(V-L) (in magnitudes), the calculated value of intrinsic V band polarization (in %), the weighted average value of $\overline{v\sin{i}}$ (in kms-1), the average value of far IR excess (E(V-12)) at 12 $\mu $m, the common name or other designation of the star and any remarks. The references to the sources of the V and L photometry, the observed polarization and the individual values of $v\sin{i}$ are given below.

References to the sources of optical and IR photometry:
Dougherty et al. (1991); SIMBAD (1999); Gezari, D. Y. et al. (1999); Hoffleit & Jaschek (1982); Sterken (1990); Grillo et al. (1992); Hillenbrand et al. (1992);
References to the sources of optical polarimetry:
Poeckert et al. (1979); McLean & Brown (1978); Hall & Mikesell (1953); Ghosh et al. (1999); WUPPOL (1999); Leroy (1993); McDavid (1999); Serkowski et al. (1975); Quirrenbach (1997); Clarke & Bjorkman (1998); Huang et al. (1989); Bjorkman et al. (1997); Coyne et al. (1967); Jian & Bhatt (1995); Yudin & Evans (1998); Vosnchinnikov & Marchenko (1982); Bjorkman & Schulte-Ladbeck (1994); McDavid (2000); Heiles (2000).
References to the sources of $v\sin{i}$ data:
SIMBAD (1999); Balona (1990); Slettebak (1982); van den Ancker et al. (1998); Corporon & Lagrange (1999); Elias et al. (1997); Bjorkman et al. (1997); WUPPOL (1999); Brown & Verschueren (1997); Howarth et al. (1997); Prinja (1993); Hirata (1993); Quirrenbach (1993); Mennickent et al. (1994); Ballereau et al. (1995); Hoffleit & Jaschek (1982); Halbedel (1996); Uesugi & Fukuda (1982); Kaper (1999); Henrichs (1999); Dachs et al. (1981); Steele et al. (1999); Carpenter et al. (1984); Levato & Maloroda (1970); Dachs et al. (1981); Coté & Waters (1987); Lyubimkov et al. (1997); Balona (1995); Short & Bolton (1994); Rivinius et al. (1999); Prosser (1992); Snow (1981); Snow (1981); Ghosh (1988); Slettebak et al. (1997); Briot (1986); Chosh et al. (1999); Doazan et al. (1981); Wolff et al. (1978); Wolff et al. (1982); Finkenzeller (1985); Balona et al. (1992); Turner et al. (1978); Slettebak (1966); Jaschek & Jaschek (1993); Conti & Ebberts (1977); Herrero (1994); Penny (1996); Bernacca & Perinotto (1970); Clark & Steele (2000)


Appendix II. Observed, interstellar and intrinsic polarization

  observed interstellar intrinsic     observed interstellar intrinsic
    polarization polarization polarization     polarization polarization polarization
HD D, pc $p_{V}\pm\sigma_{\rm p}$, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$ HD D, pc $p_{V}\pm\sigma_{\rm p}$, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$

144
301 $0.62\pm0.05$ 73 0.73 85 0.30 24 47359 1820 $1.01\pm0.20$ 8 0.5 170 0.7 20
4180 278 $0.70\pm0.13$ 85 0.5 90 0.23 74 47761 751 $2.30\pm0.20$ 169 1.8 175 0.6 152
5394 188 $0.60\pm0.25$ 111 0.3 90 0.43 125 48282 425 $0.83\pm0.04$ 165 0.6 35 1.0 146
6811 226 $0.74\pm0.12$ 90 0.6 90 0.14 90 48917 800         0.51$\otimes$ 18
7636 559 $2.59\pm0.20$ 80 2.3 85 0.51 55 49330 298 $1.71\pm0.18$ 133 0.8 150 1.14 121
10144 44 $0.04\pm0.00$ 136 0   0   49336 444 $1.30\pm0.10$ 2 0.9 50 1.65 166
10516 220 $1.80\pm0.30$ 28 0.4 105 2.17 26 49787 1445 $0.00\pm0.20$   0.7 160 0.7 70
11415 136 $0.40\pm0.17$ 125 0.2 105 0.28 139 49888 502 $0.00\pm0.20$   0.50 130 0.50 40
12302 340 $2.34\pm0.11$ 90 1.54 90 0.80 89 49977 676 $2.17\pm0.20$ 152 0.30 130 1.95 155
12856 1700 $1.20\pm0.20$ 108 2 100 0.91 179 50013 242 $0.31\pm0.10$ 106 0   0.3 106
13051 2041 2.21 88 2.2 100 0.92 49 50083 500 $1.24\pm0.20$ 24 1 170 1.25 47
13758 1620 $4.61\pm0.18$ 108 3.5 115 1.48 91 50658 253 $0.62\pm0.12$ 16 0.2 50 0.6 4
13890 2000 $3.46\pm0.18$ 107 3.3 115 0.95 71 50696 1740 $0.23\pm0.18$ 139 0.8 150 0.6 64
14422 1950 $3.09\pm0.18$ 117 3.5 115 0.47 11 51354 398 $0.92\pm0.20$ 140 0.2 15 1.0 135
14605 1820 $3.78\pm0.20$ 118 3.5 115 0.47 144 51480 160 $0.37\pm0.20$ 173 0.4 130 0.55 17
15450 725 $3.87\pm0.20$ 122 3.5 115 0.97 152 52244 1660 $0.69\pm0.18$ 13 0.7 120 1.33 22
18552 341 $\odot $       0.38 104 52437 407 $0.16\pm0.10$ 81 0.2 100 0.12 136
18877 1820 $2.12\pm0.20$ 126 2 120 0.45 160 52721 909 $1.14\pm0.15$ 17 0.4 135 1.4 24
19243 617 $2.21\pm0.20$ 129 1.9 119 0.78 158 52812 460 $0.88\pm0.20$ 39 0.3 160 1.05 46
20017 503 $2.86\pm0.20$ 126 2.6 120 0.62 156 52918 342 $0.00\pm0.20$   0.4 130 0.4 40
20134 394 $1.75\pm0.20$ 110 2.4 120 0.90 48 53367 830 $0.60\pm0.20$ 30 0.2 130 0.75 32
20336 246 $0.43\pm0.08$ 142 1.0 128 0.65 29 54309 380 $0.65\pm0.10$ 1 0.3 30 0.55 167
20418 147 $0.34\pm0.00$ 101 0.25 110 0.13 83 54464 1000 $0.00\pm0.20$   0   0  
21212 407 $4.06\pm0.20$ 136 2.7 123 2 154 54786 2100 $0.78\pm0.18$ 116 0.5 170 1 102
21362 170 $0.31\pm0.00$ 112 0.4 110 0.1 14 55135 420 $0.00\pm0.20$   0.3 130 0.30 40
21455 177 $0.55\pm0.32$ 106 0.5 111 0.10 78 55538 1800 $1.15\pm0.20$ 171 0.5 170 0.65 172
21551 267 $0.51\pm0.15$ 127 1.3 120 0.85 26 55606 2500 $0.55\pm0.18$ 60 0   0.55 60
21641 220         0.26$\otimes$ 129 56014 483 $0.62\pm0.05$ 85 0.4 90 0.25 76
21650 314 $0.65\pm0.20$ 151 0.9 130 0.6 17 56139 283 $0.20\pm0.15$ 60 0.2 80 0.14 25
22192 215 $0.80\pm0.15$ 45 1.0 117 1.7 35 56806   $0.65\pm0.20$ 178 0.7 165 0.3 41
22298 360 $2.67\pm0.12$ 119 1.55 120 1.12 118 57150 260 $0.70\pm0.04$ 87 0.15 30 0.77 92
22780 248 $0.51\pm0.05$ 144 0.6 110 0.47 174 57219 256 $0.12\pm0.04$ 32 0.15 30 0.03 113
23016 125 $0.60\pm0.04$ 87 0.3 120 0.55 72 57386 1250 $0.55\pm0.18$ 141 0.4 135 0.18 154
23302 114 $0.32\pm0.05$ 128 0.3 120 0.09 162 57393 2400 $0.49\pm0.15$ 78 0.3 130 0.6 65
23478 239 $1.71\pm0.20$ 29 0.8 7 1.3 42 57539 483 $0.00\pm0.20$   0.5 120 0.5 30
23480 110 $0.37\pm0.02$ 135 0.3 120 0.18 162 58011 1085 $0.36\pm0.10$ 111 0.35 120 0.1 73
23552 182 $0.55\pm0.05$ 140 0.4 140 0.16 154 58050 691 $0.06\pm0.00$ 78 1.1 25 1.12 156
23630 113 $0.18\pm0.02$ 117 0.3 120 0.12 34 58343 290 $0.88\pm0.20$ 164 0.5 170 0.40 157
23800 427 $2.67\pm0.20$ 122 1.55 130 1.26 112 58715 52 $0.14\pm0.13$ 90 0   0.14 90
23862 119 $0.43\pm0.03$ 90 0.3 120 0.38 69 58978 435 $1.10\pm0.30$ 161 0.25 160 0.85 161
24479 100 $0.06\pm0.03$ 146 0.27 136 0.21 43 59094 870 $0.51\pm0.18$ 118 0.6 110 0.18 173
24534 826 0.88 43 1 57 0.48 178 59498 1050 $0.64\pm0.10$ 115 0.6 120 0.12 82
25348 1260 $1.34\pm0.20$ 124 0.5 95 1.16 135 60848 498 $0.16\pm0.25$ 56 0.25 25 0.22 96
25799 360 $0.37\pm0.20$ 102 0.8 95 0.45 179 60855 508         0.31$\oslash$  
25940 170 $0.25\pm0.10$ 145 0.25 165 0.17 110 61355   $0.41\pm0.10$ 102 0.8 140 0.8 65
26356 210 $0.00\pm0.20$   0.06 136 0.06 46 62532 1580 $0.46\pm0.18$ 127 0.45 165 0.55 101
26420 182 $0.78\pm0.20$ 137 0.3 165 0.66 126 62654 1380 $1.63\pm0.10$ 163 1 170 0.7 153
26906 550 $2.17\pm0.20$ 144 1.1 155 1.22 134 62753 298 $0.72\pm0.10$ 15 0.15 45 0.65 9
28497 483 $0.90\pm0.20$ 128 0.3 180 1.02 120 62780 4170 $1.65\pm0.10$ 128 0.5 70 1.90 135
29866 166 $1.98\pm0.20$ 6 0.8 10 1.19 3 63150 1820 $2.01\pm0.10$ 137 1 160 1.5 123
30076 412 $0.40\pm0.20$ 169 0.3 180 0.17 148 63359 2630 $0.26\pm0.06$ 25 0.8 150 0.9 52
32190 575 $0.78\pm0.20$ 80 0.7 80 0.08 80 63462 315 $0.00\pm0.20$   0.2 100 0.2 10
32343 206 $0.51\pm0.05$ 168 0.4 165 0.12 178 64298 524 $0.75\pm0.10$ 122 0.1 100 0.68 125
32990 302 $1.34\pm0.20$ 88 0.7 80 0.69 96 65719 1660 $0.65\pm0.20$ 14 0.5 15 0.15 11
32991 316 $0.80\pm0.35$ 95 0.7 80 0.40 126 65875 315 $0.15\pm0.20$ 15 0   0.15 15
33152 955 $1.57\pm0.20$ 4 1.4 150 1.67 30 66194 315 $0.65\pm0.05$ 138 0.35 145 0.32 130
33232 324 $1.15\pm0.20$ 140 1.0 165 0.92 112 69168 310 $0.26\pm0.10$ 80 0.1 80 0.16 80
33328 538 $0.11\pm0.00$ 78 0.3 110 0.24 31 69404 365 $0.56\pm0.10$ 120 0.2 100 0.4 129
33461 372 $1.84\pm0.20$ 165 1.2 165 0.64 165 69425 2290 $0.72\pm0.10$ 131 1.5 110 1.11 7
33599 794 $0.68\pm0.05$ 30 0.1 90 0.7 30 71934 830 $0.82\pm0.10$ 13 0.25 180 0.6 18
33604 603 $1.29\pm0.20$ 168 1.5 160 0.44 43 72014 315 $0.56\pm0.10$ 126 0.1 130 0.46 125
33988 240 $0.78\pm0.20$ 161 1 160 0.22 66 72063 2000 $1.17\pm0.10$ 107 0.5 130 0.9 95
34921 1515 $3.73\pm0.20$ 146 2 160 2 133 72067 490 $0.02\pm0.02$ 160 0.2 180 0.2 92
34959 382 $0.94\pm0.03$ 65 0.3 80 0.7 59 74401 1510 $0.74\pm0.10$ 81 0.6 160 1.3 76
35165 581 $0.77\pm0.04$ 6 0.1 10 0.7 5 75658 690 $0.65\pm0.10$ 138 0.45 160 0.45 20
35345 1115 $2.95\pm0.20$ 155 2.5 160 0.65 134 76534 411 $0.49\pm0.05$ 124 1 130 0.53 46
35411 276 $0.10\pm0.06$ 168 0.1 70 0.20 165 77032 1200 $1.74\pm0.10$ 123 0.6 120 1.14 124
35439 340 $0.35\pm0.07$ 122 0.3 80 0.46 142 77320 307 $0.85\pm0.10$ 130 0.57 70 1.24 142
36012 391 $0.24\pm0.03$ 72 0.3 80 0.10 12 78764 251 $0.28\pm0.04$ 125 0.2 125 0.08 125
36576 575 $0.11\pm0.00$ 75 1.15 25 1.17 113 79778 830 $1.00\pm0.10$ 145 0.8 145 0.2 145
37115 543 $0.37\pm0.03$ 89 0.4 60 0.37 121 80834 795 $1.55\pm0.10$ 111 1.0 100 0.73 127
37202 128 $1.40\pm0.15$ 31 0.3 20 1.13 34 81654 724 $0.47\pm0.10$ 131 1.1 120 0.7 23
37330 493 $0.66\pm0.03$ 63 0.4 65 0.26 60 82830 3980 $0.86\pm0.10$ 128 1.4 10 2.0 110
37490 498 $0.43\pm0.10$ 48 0.45 65 0.27 9 83043 1050 $1.16\pm0.13$ 162 2.0 155 0.92 56
37657 363 $1.66\pm0.20$ 174 0.4 160 1.32 178 83060 1260 $1.21\pm0.10$ 108 1.7 110 0.5 25
37795 82 $0.15\pm0.05$ 109 0   0.15 109 83597 2400 $1.24\pm0.07$ 151 3.0 155 1.78 68
37967 337 $0.78\pm0.20$ 8 0.3 85 1.1 4 83953 152 $0.27\pm0.03$ 176 0.05 75 0.32 174
38010 262 $1.77\pm0.08$ 158 1.5 5 0.33 131 84523 525 $0.26\pm0.10$ 122 0.5 120 0.25 28
38087 199 $2.53\pm0.06$ 118 0.2 65 2.5 122 84567 550 $0.75\pm0.04$ 74 0.5 75 0.25 73
38191 2400 $1.89\pm0.20$ 156 1.5 150 0.5 174 86272 1050 $0.89\pm0.10$ 118 0.8 100 0.5 149
38708 724 $1.15\pm0.18$ 167 2.2 170 1.06 83 86612 193 $0.04\pm0.04$ 10 0.03 10 0.01 10
39340 794 $2.30\pm0.20$ 171 2.2 170 0.13 10 86689 3800 $0.20\pm0.10$ 168 0.6 110 0.7 13
39478 912 $0.00\pm0.12$   2 170 2.0 80 87380 2890 $1.34\pm0.10$ 127 1.0 130 0.2 84
40193 650 $0.48\pm0.07$ 70 0.4 40 0.4 96 87543 250 $0.50\pm0.10$ 107 0.3 105 0.20 110
40978 460 $1.06\pm0.20$ 6 0.5 180 0.58 11 87901 83.5 $0.06\pm0.12$ 46 0.1 80 0.1 23
41335 282 $0.55\pm0.28$ 147 0.05 60 0.60 147 89080   $0.20\pm0.05$ 100 0.6 120 0.45 38
42054 323 $0.01\pm0.05$ 35 0   0   90187 3020 $1.84\pm0.10$ 115 1.5 120 0.45 96
42545 238 $0.00\pm0.20$   0.1 45 0.1 135 90563 1100 $1.77\pm0.10$ 135 1.5 120 0.9 164
43285 228 $0.03\pm0.07$ 61 0.1 45 0.08 129 91120 149 $0.23\pm0.05$ 89 0   0.23 89
43544 256 $0.14\pm0.06$ 46 0.2 45 0.05 133 91188 794 $0.34\pm0.10$ 105 1.2 150 1.25 68
43703 1400 $1.75\pm0.20$ 142 0.5 155 1.3 137 91465 152 $0.90\pm0.10$ 74 0.35 140 1.16 68
44458 513 $0.84\pm0.08$ 79 0.35 50 0.72 91 92027 870 $1.15\pm0.10$ 111 0.5 100 0.71 119
44506 617         0.39$\otimes$ 92 92061 2890 $0.94\pm0.10$ 99 0.9 100 0.05 80
44637 398 $1.84\pm0.20$ 1 1.3 175 0.6 14 92714 1200 $0.37\pm0.10$ 31 0.8 100 1.1 16
45314 457 $1.38\pm0.20$ 171 1.4 175 0.2 124 92938 140 $0.17\pm0.04$ 147 0.4 140 0.24 45
45542 154 $0.22\pm0.12$ 17 0.15 5 0.10 35 93030 135 $0.38\pm0.10$ 139 0.4 140 0.02 67
45626 457 $2.03\pm0.20$ 157 2 175 1.25 122 93237 307 $0.74\pm0.04$ 137 0.5 140 0.25 131
45725 212 $0.39\pm0.15$ 0.8 0.2 165 0.24 14 93561   $0.89\pm0.10$ 105 0.8 140 1.0 80
45726 212 $0.08\pm0.05$ 155 0.2 165 0.13 81 93683 1260 $0.98\pm0.10$ 146 1 80 1.8 158
45910 760 1.06 150 0.5 170 0.70 135 94648 1260 $1.29\pm0.10$ 78 1 80 0.3 72
45995 435 $0.78\pm0.25$ 132 0.4 180 0.91 119 96357 830 $1.50\pm0.10$ 130 1 100 1.3 150
46380 575 $1.80\pm0.20$ 178 0.6 10 1.28 172 96864 1380 $1.34\pm0.10$ 150 1.5 120 1.4 3
47054 256         0.34$\otimes$ 71 98624 2290 $0.79\pm0.10$ 119 1 80 1.1 149


Appendix II. Observed, interstellar and intrinsic polarization

  observed interstellar intrinsic     observed interstellar intrinsic
    polarization polarization polarization     polarization polarization polarization
HD D, pc $p_{V}\pm\sigma_{\rm p}$, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$ HD D, pc $p_{V}\pm\sigma_{\rm p}$, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$

98927
1510 $1.48\pm0.10$ 63 1.0 80 0.8 43 160886 1000 $0.97\pm0.20$ 59 1.3 57 0.34 141
99354 2750 $1.39\pm0.10$ 72 1.3 90 0.84 35 161103 830 $4.83\pm0.12$ 172 4.0 175 0.95 158
100199 2290 $0.86\pm0.00$ 84 1.3 90 0.5 11 161261 452 $0.81\pm0.05$ 82 0.75 85 0.1 57
100324 912 $4.26\pm0.10$ 136 3.5 120 2 164 161774   $1.44\pm0.10$ 164 0.9 160 0.55 171
100889 93 $0.03\pm0.03$ 33 0.07 35 0.04 128 161807 383 $1.73\pm0.10$ 177 1.4 175 0.35 5
102742 1200 $1.10\pm0.10$ 86 1.0 90 0.15 61 162352   $2.01\pm0.10$ 173 1.5 175 0.5 166
105435 121 $0.33\pm0.07$ 137 0   0.33 137 162568 253 $1.06\pm0.10$ 179 0.65 177 0.41 3
105521 330 $0.31\pm0.04$ 30 0.07 111 0.38 28 162732 368 $0.31\pm0.05$ 67 0.45 160 0.76 69
105675 2890 $1.74\pm0.10$ 59 1.2 90 1.55 38 163454 1200 $1.67\pm0.15$ 50 1.3 170 2.57 63
105753 3980 $0.30\pm0.10$ 74 1.2 90 0.7 41 163868 600 $0.45\pm0.10$ 141 1.0 150 0.59 67
107348 118 $0.10\pm0.05$ 132 0.07 140 0.04 22 164284 207 $0.85\pm0.25$ 92 0.5 75 0.52 108
109387 153 $0.25\pm0.10$ 24 0.1 60 0.24 12 164447 498 $0.29\pm0.04$ 146 0.55 175 0.45 101
110335 317 $0.46\pm0.04$ 89 1.45 75 1.05 160 164906 1050 $0.37\pm0.20$ 174 0.9 180 0.55 94
110432 301 $1.77\pm0.11$ 81 0.45 80 1.3 81 165063 377 $0.70\pm0.10$ 147 0.8 160 0.35 100
110863 760 $4.47\pm0.06$ 93 2.8 85 1.94 105 165285 1580 $1.04\pm0.14$ 56 0.6 120 1.5 47
112078 122 $0.05\pm0.04$ 169 0.05 125 0.07 13 165921 541 $0.74\pm0.04$ 100 0.5 120 0.48 79
112091 111 $0.17\pm0.04$ 128 0.05 130 0.12 127 166014 106 $0.17\pm0.01$ 179 0   0.17 179
112999 336 $1.82\pm0.10$ 78 2.2 90 0.9 27 166443 1510 $1.63\pm0.20$ 145 0.5 110 1.53 154
113120 483 $1.18\pm0.15$ 115 1.1 105 0.4 149 166524 2290 $0.51\pm0.18$ 105 0.8 50 1.09 127
113605 1445 $1.71\pm0.10$ 80 2.0 90 0.7 28 166566 1380 $0.97\pm0.20$ 45 1.0 30 0.51 84
113902 99 $0.03\pm0.04$ 107 0.05 130 0.04 58 167128 228 $0.98\pm0.10$ 3 0.9 10 0.24 151
114200 3630 $1.40\pm0.10$ 92 1.2 100 0.4 64 168797 360 $0.78\pm0.20$ 64 0.60 65 0.18 61
114800 382 $0.72\pm0.10$ 109 1.8 75 1.7 153 168957 513 $0.78\pm0.20$ 176 0.65 180 0.16 159
114981 935 $0.14\pm0.04$ 32 0.15 35 0.02 152 169033 188 $1.06\pm0.20$ 111 0.8 125 0.52 88
116781 1995 $1.46\pm0.10$ 81 2.2 75 0.8 155 169805 1260 $0.83\pm0.10$ 141 1 140 0.15 45
117111 1050 $0.89\pm0.15$ 78 1.5 80 0.6 52 170061   $1.19\pm0.19$ 71 1.5 70 0.3 156
117357 1995 $3.03\pm0.10$ 74 2.2 75 0.8 71 170235 603 $0.82\pm0.10$ 175 0.5 4 0.38 163
118246 660 $0.29\pm0.05$ 83 0.25 80 0.05 99 170835 427 $1.82\pm0.10$ 21 0.9 180 1.3 35
120324 162 $0.07\pm0.05$ 169 0.07 170 0   171348 476 $1.08\pm0.09$ 174 0.9 180 0.27 152
120991 630 $0.47\pm0.10$ 84 0.4 80 0.09 102 171406 455 $0.28\pm0.20$ 13 0.5 180 0.28 19
121556 760 $0.47\pm0.47$ 129 1.6 80 1.73 162 171757 3980 $0.43\pm0.10$ 36 0.8 60 0.6 166
121847 104 $0.30\pm0.05$ 65 0.25 60 0.04 9 171780 318 $0.28\pm0.20$ 171 0.4 180 0.16 106
122450 833 $1.37\pm0.15$ 129 1.7 80 0.66 163 172158 2090 $0.54\pm0.10$ 143 1.1 180 1.08 104
122669 1510 $2.35\pm0.10$ 64 2.2 70 0.48 31 172252 725 $4.65\pm0.20$ 148 4.5 150 0.35 117
122691 1660 $1.82\pm0.10$ 87 2.2 70 1.2 132 172256 760 $0.81\pm0.12$ 169 0.7 180 0.3 140
124367 149 $0.11\pm0.08$ 120 0.3 70 0.35 150 173219 1260 $0.65\pm0.20$ 41 2.0 45 1.83 156
124771 169 $0.67\pm0.04$ 112 0.3 110 0.37 114 173370 145 $0.13\pm0.00$ 81 0.12 73 0.04 118
125159   $1.12\pm0.10$ 62 1 70 0.3 33 173637 1900 $1.15\pm0.20$ 87 1.7 45 1.95 117
127489 535 $1.58\pm0.10$ 62 2 65 0.46 166 173948 556 $0.62\pm0.10$ 21 0.15 20 0.50 20
127972 94.6 $0.37\pm0.07$ 174 0.1 75 0.47 172 174237 667 $0.18\pm0.15$ 80 0   0.18 80
129954 351 $1.06\pm0.04$ 65 1.3 80 0.67 17 174513 2180 $0.00\pm0.20$   1.8 45 1.8 135
131492 256 $0.46\pm0.04$ 65 0.9 75 0.5 175 174571 460 $2.90\pm0.20$ 80 1.7 80 1.2 80
133738 115 $0.95\pm0.10$ 52 0.15 60 0.81 51 174638 270 $0.60\pm0.15$ 155 0.15 155 0.45 155
134401 1260 $0.62\pm0.10$ 13 1.1 55 1.2 161 175863 400 $0.00\pm0.20$   0.8 110 0.8 20
135160 558 $1.18\pm0.04$ 54 1.5 60 0.4 168 175869 338 $0.04\pm0.04$ 48 0.5 60 0.46 151
136415 156 $0.56\pm0.10$ 83 0.3 65 0.36 97 177015 800 $0.51\pm0.20$ 0 0.8 40 1.87 148
136556 1900 $2.00\pm0.10$ 34 2 55 1.45 179 177648 279 $1.15\pm0.20$ 40 0.5 25 0.76 50
137387 313 $0.93\pm0.04$ 122 0.65 135 0.45 102 178175 469 $0.35\pm0.30$ 0 0.72 45 0.80 148
137432 128 $0.09\pm0.04$ 91 0.1 65 0.08 125 178475 255 $0.51\pm0.20$ 138 0.3 140 0.21 135
137518 4170 $0.65\pm0.10$ 41 1.5 55 1.0 154 181409 568 $0.37\pm0.20$ 163 0.5 145 0.30 31
138749 95.3 $0.20\pm0.20$ 90 0.05 100 0.15 87 181615 513 $1.38\pm0.20$ 172 0.7 172 0.68 172
138769 133 $0.08\pm0.04$ 66 0.05 45 0.05 85 183362 525 $0.75\pm0.20$ 42 0.3 0 0.78 53
139790 1445 $0.80\pm0.10$ 36 2.5 50 1.8 146 183656 295 $0.90\pm0.22$ 60 0.4 70 0.54 53
140336 3800 $1.17\pm0.10$ 49 1.7 55 0.6 156 184279 600 $0.00\pm0.20$   0.9 100 0.9 10
140784 119 $0.04\pm0.04$ 32 0.1 70 0.1 171 184915 446 $1.35\pm0.33$ 172 2.4 180 1.17 99
140926 578 $1.64\pm0.10$ 43 1.5 50 0.42 11 185037 226 $0.15\pm $ 77 0.15 75 <0.05 121
140946 1095 $1.31\pm0.10$ 60 1.5 50 0.5 111 187350 322 $0.78\pm0.20$ 82 1.6 90 0.85 7
141637 160 $0.97\pm0.20$ 34 0.4 45 0.62 27 187567 476 $0.51\pm0.20$ 114 1.35 70 1.43 31
141926 1445 $1.74\pm0.10$ 66 2 50 1.05 110 187811 190 $0.00\pm0.20$   0.15 5 0.15 96
142184 120 $0.65\pm0.20$ 64 0.5 60 0.17 76 187851 368 $1.11\pm0.18$ 24 0.55 40 0.71 12
142237 1095 $1.41\pm0.10$ 55 2 50 0.65 129 189687 483 $0.20\pm0.10$ 110 0.4 90 0.28 166
142926 148 $0.16\pm0.05$ 160 0   0.16 160 190944 1510 $1.34\pm0.20$ 24 0.4 15 0.97 28
142983 157 $0.85\pm0.15$ 138 0.65 110 0.73 162 191610 264 $0.35\pm0.15$ 56 0.15 90 0.33 43
144320 1260 $1.15\pm0.10$ 48 2 50 0.85 143 191639 860 $0.51\pm0.20$ 4 0.3 180 0.22 10
144970 1660 $2.86\pm0.13$ 44 2.5 50 1.0 32 192044 350 $0.15\pm0.05$ 160 0.30 90 0.43 173
145846 630 $3.24\pm0.11$ 55 3 50 0.85 86 192445 1860 $0.37\pm0.20$ 174 0.7 175 0.33 86
146444 760 $1.46\pm0.10$ 24 2.5 35 1.25 138 192685 368 $0.00\pm0.20$   0.2 57 0.2 148
146463 725 $0.68\pm0.10$ 31 2 50 1.5 148 193009 860 $0.65\pm0.20$ 75 1.5 170 2.1 78
147274 2290 $1.51\pm0.10$ 35 1 45 0.65 20 193182 285 $0.47\pm0.10$ 134 0.35 140 0.15 119
147302 1320 $2.32\pm0.10$ 52 2 50 0.35 60 193911 552 $0.00\pm0.05$   0.43 57 0.43 147
147756 2090 $1.39\pm0.10$ 24 1.5 25 0.1 127 194335 274 $0.00\pm0.20$   0.35 70 0.35 160
148184 150 $0.40\pm0.05$ 110 0.7 125 0.41 50 194883 769 $0.00\pm0.20$   1.6 160 1.6 70
148259 457 $1.27\pm0.10$ 19 1.6 20 0.3 114 195325 174 $0.36\pm0.07$ 63 0.2 70 0.17 55
148877   $0.83\pm0.10$ 39 1 45 0.25 156 195407 1360 $1.80\pm0.20$ 44 1.6 65 1.23 14
149298 1200 $0.82\pm0.10$ 156 0.8 35 1.3 141 196712 377 $0.35\pm0.04$ 95 0.4 95 0.05 2
149313 366 $1.69\pm0.10$ 30 1.4 25 0.39 49 197419 360 $0.00\pm0.20$   0.33 45 0.33 135
149671 211 $0.57\pm0.04$ 48 0.5 40 0.16 89 198183 360 $0.17\pm0.12$ 81 0.33 45 0.32 120
149729 1380 $1.24\pm0.10$ 49 0.9 45 0.38 60 198512 1000 $1.66\pm0.20$ 126 2.4 150 1.8 82
149757 140 $0.70\pm0.60$ 126 0.7 90 0.82 153 198625 282 $0.00\pm0.20$   0.25 65 0.25 155
152060 2190 $0.73\pm0.10$ 23 0.8 35 1.2 175 198895 397 $5.39\pm0.20$ 149 2.5 135 3.4 159
152478 230 $1.26\pm0.12$ 19 0.3 25 0.97 17 198931 752 $4.00\pm0.29$ 147 2.8 160 1.92 143
152541 380 $0.93\pm0.10$ 21 0.6 26 0.35 14 199218 207 $0.37\pm0.20$ 60 0.3 80 0.24 43
152979 1660 $1.69\pm0.10$ 26 1.6 25 0.1 37 199356 645 $2.17\pm0.20$ 151 2 160 0.65 118
153261 363 $1.57\pm0.05$ 24 0.8 40 0.99 11 200120 345 $0.45\pm0.10$ 22 0.3 65 0.52 5
153295 2290 $1.84\pm0.10$ 33 0.8 35 1 32 200310 418 $0.45\pm0.05$ 100 0.33 60 0.51 120
153879 1660 $1.62\pm0.10$ 13 1.0 25 0.8 178 201522 418 $0.97\pm0.20$ 15 0.33 60 1.0 6
154040 630 $1.15\pm0.50$ 86 0.6 35 1.4 98 201733 336 $0.97\pm0.20$ 172 0.3 62 1.2 168
154111 1380 $1.29\pm0.10$ 35 1.6 30 0.4 104 202904 276 $0.33\pm0.05$ 111 0.15 40 0.46 117
154154 1820 $2.72\pm0.10$ 21 1.0 25 1.7 18 203025 525 $0.18\pm0.20$ 11 0.8 20 0.63 113
154243 1050 $1.41\pm0.10$ 22 0.8 90 2.0 14 203064 1030 $0.37\pm0.20$ 55 0.15 65 0.23 49
154450 1820 $1.00\pm0.20$ 90 1.25 140 1.7 67 203374 830 $0.37\pm0.20$ 166 1 35 1.1 134
154911 2190 $1.66\pm0.15$ 149 1.65 155 0.35 107 203467 331 $0.50\pm0.25$ 122 0.5 120 0.03 166
155438 2750 $1.68\pm0.10$ 28 1.1 25 0.6 33 203699 600 $0.18\pm0.20$ 33 0   0.18 33
155806 660 $0.84\pm0.09$ 150 0.7 140 0.30 165 203731 309 $0.74\pm0.20$ 167 0.27 65 1.0 164
155851 1445 $2.18\pm0.21$ 146 1.25 140 1.0 154 204116 725 $2.95\pm0.20$ 22 1.8 25 1.18 17
156325 386 $2.01\pm0.08$ 156 0.5 140 1.6 161 204722 780 $1.20\pm0.20$ 10 2.0 45 1.95 153
156468 1000 $1.00\pm0.10$ 9 1.5 180 0.65 75 204860 483 $0.00\pm0.20$   0.2 45 0.2 135
157042 221 $0.26\pm0.04$ 151 0.25 30 0.44 136 205060 461 $0.97\pm0.20$ 32 0.22 50 0.8 27
158319 725 $0.78\pm0.20$ 70 1.5 55 0.9 132 205618 990 $1.24\pm0.20$ 26 0.6 50 0.95 12
158427 74 $0.61\pm0.04$ 174 0.15 30 0.58 166 205637 203 $1.20\pm0.25$ 156 0   1.20 156
158643 131 $0.46\pm0.10$ 30 0.1 120 0.56 30 206773 498 $2.03\pm0.20$ 169 1.75 170 0.29 163
159489 3800 $1.32\pm0.10$ 22 1.0 20 0.35 27 208057 157 $0.09\pm0.04$ 119 0.19 32 0.24 144
160202 532 $1.32\pm0.13$ 161 1.7 165 0.42 87 208220 2600 $1.94\pm0.20$ 42 2.0 35 0.48 87


Appendix II. Observed, interstellar and intrinsic polarization

  observed interstellar intrinsic
    polarization polarization polarization
HD D, pc $p_{V}\pm\sigma_{\pm p}$, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$ pV, % $\theta$, $^\circ$

208392
910 $1.34\pm0.20$ 44 1 45 0.34 41
208682 369 $1.00\pm0.30$ 140 0.5 120 0.70 154
209014 311 $0.15\pm0.10$ 15 0   0.15 15
209409 117 $0.52\pm0.05$ 177 0.2 125 0.60 6
209522 346 $0.19\pm0.04$ 19 0   0.19 19
210129 214 $0.28\pm0.04$ 7 0.12 55 0.32 176
212044 860 $1.26\pm0.20$ 52 1.7 47 0.51 124
212076 298 $0.25\pm0.10$ 98 0.26 112 0.12 58
212571 338 $0.93\pm0.75$ 168 0.3 127 0.94 177
214167 196 $0.00\pm0.20$   0.20 110 0.2 20
214168 77 $0.13\pm0.20$ 30 0.05 120 0.18 30
214748 228 $0.09\pm0.10$ 155 0.30 100 0.34 3
215227 256 $0.66\pm0.12$ 28 0.60 83 1.05 12
215605 1995 $1.45\pm0.18$ 40 2.6 60 1.76 166
216057 185 $0.38\pm0.03$ 44 0.75 50 0.39 146
216200 333 $0.89\pm0.20$ 145 0.8 75 1.6 154
217050 337 $1.55\pm0.20$ 75 0.8 75 0.77 67
217061 795 $1.22\pm0.20$ 88 1.5 95 0.43 27
217543 273 $0.00\pm0.20$   0.4 85 0.4 175
217675 212 $0.34\pm0.12$ 90 0.45 85 0.13 161
217891 151 $0.28\pm0.06$ 109 0.22 102 0.09 128
218393 446 $0.72\pm0.10$ 55 0.9 65 0.33 179
218674 525 $0.65\pm0.05$ 90 0.9 80 0.36 151
219688 98.7 $0.13\pm0.10$ 152 0.05 152 0.08 152
220058 1995 $1.17\pm0.20$ 67 1.2 65 0.1 121
220116 535 $4.21\pm0.18$ 81 2.5 85 1.77 75
223387 1995 $2.11\pm0.20$ 67 1.2 65 0.9 70
224544 571 $0.75\pm0.08$ 66 0.65 100 0.79 41
224559 417 $0.48\pm0.12$ 37 0.55 50 0.24 170
224686 115 $0.08\pm0.20$ 86 0.04 88 0.04 84
224905 1510 $1.03\pm0.20$ 100 1.5 75 1.15 143
225095 358 $1.27\pm0.20$ 79 0.85 65 0.66 93
225985 2100 $0.51\pm0.18$ 149 0.5 80 0.9 159
227836 2750 $1.80\pm0.20$ 82     1.8$\dagger$ 82
228104 1750 $0.50\pm0.20$ 70 0.45 160 0.95 70
228438 3500 $1.15\pm0.20$ 170 1.0 170 0.15 170
228860 1995 $1.38\pm0.18$ 102 0.5 80 1.08 110
229171 1995 $0.78\pm0.20$ 20 1.5 180 1.0 75
230579 1200 $1.84\pm0.18$ 99 0.7 80 1.35 109
232552 306 $2.21\pm0.20$ 117 1.2 110 1.09 125
235795 2180 $0.89\pm0.18$ 40 2.0 48 1.2 144
236689 1580 $2.72\pm0.18$ 91 2.5 90 0.25 101
236935 1510 $4.29\pm0.18$ 91 3 95 1.4 82
237056 780 $5.90\pm0.18$ 125 5.5 118 0.9 152
239758 2090 $2.12\pm0.18$ 59 1.5 45 1.1 80
244894 2290 $1.61\pm0.18$ 19 1 50 1.45 0
245493 1050 $1.11\pm0.18$ 165 1 160 0.2 12
246878 2500 $0.55\pm0.18$ 133 1 180 1.1 104
248753 395 $2.12\pm0.20$ 139 0.9 165 1.7 127
249695 1820 $1.06\pm0.18$ 176 1.2 170 0.25 54
250028 1000 $4.29\pm0.18$ 164 3.5 175 1.7 138
250163 1450 $1.66\pm0.18$ 136 2 165 1.8 100
250289 546 $2.95\pm0.18$ 162 1.95 165 1 156
254647 2630 $1.11\pm0.18$ 11 0.6 180 0.6 22
256577 1995 $1.61\pm0.18$ 148 0.6 170 1.3 140
298298 1900 $1.37\pm0.16$ 158 1.5 170 0.6 113
300584 1820 $1.14\pm0.10$ 52 0.5 150 1.6 54
302724 1320 $1.40\pm0.10$ 59 0.8 80 1 42
302838 2290 $0.97\pm0.10$ 157 1.2 150 0.4 40
305382 1900 $1.04\pm0.10$ 145 1.5 100 1.8 173
306209 3150 $1.65\pm0.10$ 94 1.1 95 0.6 90
306962   $1.80\pm0.10$ 80 1.4 100 1.2 55
307350 1820 $0.87\pm0.10$ 91 1.2 100 0.5 28
312973 1900 $0.69\pm0.25$ 147 0.8 110 0.9 175
316568 1380 $1.65\pm0.08$ 13 1.2 180 0.8 35
316587 3000 $0.51\pm0.18$ 155 1.2 180 1 125
316589 2550 $1.20\pm0.18$ 19 1.2 180 0.8 55
CD-30 5559   $0.92\pm0.10$ 171 0.9 150 0.7 25
CPD-60 4551 461 $1.71\pm0.10$ 97 1.5 85 0.71 128
CPD-60 4708   $1.42\pm0.10$ 73 1.5 80 0.38 25
BD-13 2040   $0.65\pm0.20$ 14 0.9 175 0.6 60
BD-13 4936 1250 $1.61\pm0.18$ 101 0.9 80 1.1 35
BD+35 1169 1500 $1.66\pm0.18$ 133 1.4 150 0.9 105
BD+41 3731 2500 $0.35\pm0.15$ 125 0.9 90 0.85 169
BD+47 3302 1650 $1.20\pm0.18$ 0 1 20 0.8 155
BD+49 3735 2400 $1.67\pm0.18$ 35 1.4 40 0.4 15
BD+53 2964 1650 $1.17\pm0.18$ 61 2.0 50 1 125
BD+56 473 1150 $4.38\pm0.18$ 111 3.5 120 1.5 90
BD+56 484 2290 $3.46\pm0.18$ 124 3.5 120 0.5 170
BD+56 493 2290 $3.64\pm0.18$ 126 3.5 120 0.8 165
BD+56 582   $3.69\pm0.20$ 106 3.5 120 1.7 70
BD+56 624   $3.13\pm0.20$ 107 3.5 120 1.5 61
BD+57 515 1900 $4.29\pm0.18$ 111 4 115 0.65 80
BD+57 607   $3.82\pm0.20$ 117 4 115 0.3 177
BD+58 458 1500 $4.70\pm0.18$ 115 4.5 115 0.2 115
BD+59 2829 3150 $1.38\pm0.18$ 74 1.3 80 0.3 40
$\dagger$ - observed polarization.
$\odot $ - no objects in 3$^\circ$-vicinity, $p_{\rm intr}$ from Ghosh et al. (1999).
$\otimes$ - $p_{\rm intr}$ from Ghosh et al. (1999).
$\oslash$ - $p_{\rm intr}$ from McLean & Brown (1978) reduced to V band.

The columns in this table give HD number or other identification, the distance to the object in parsec (marked by italic when it was derived from reddening or from an absolute magnitude-spectral type/luminosity calibration), the value of observed V band polarization with its standard deviation ( $p_{\rm obs}$ in percents and $\theta_{\rm obs}$ in degrees), the estimated value of interstellar polarization ( $p_{\rm is}$ in percents and $\theta_{\rm is}$ in degrees), the calculated value of intrinsic polarization ($p_{\ast }$ in percents and $\theta_{\ast}$ in degrees).


Copyright ESO 2001