EDP Sciences
Free Access
Issue
A&A
Volume 581, September 2015
Article Number A60
Number of page(s) 33
Section Stellar structure and evolution
DOI https://doi.org/10.1051/0004-6361/201526705
Published online 02 September 2015

Online material

Appendix A: Modelled stars

Here we present the observations and models for the stars not included in the body of the paper. In each instance, we present all new data from IRAM and HIFI – black histograms – overplotted with model results for the parameters given in Table 5. For those stars that were not observed with IRAM, we include archival CO (1 → 0) and (2 → 1) lines from various

telescopes as available. These archival lines are indicated by an * next to the telescope name in the plot and allow us to present an overview of our models from low- to high-J. R Hor is the only star for which these low-J lines were not available. Our model for R Hor still incorporates some low-J lines as noted in Table C.1.

The plots for C stars are shown in Fig. A.1, for S stars in Fig. A.2 and for M stars in Fig. A.3.

thumbnail Fig. A.1

Models (blue) and observed data (black) of C stars, plotted with respect to LSR velocity. An * next to the telescope name indicates that archival data is plotted.

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thumbnail Fig. A.2

Models (blue) and observed data (black) of S stars, plotted with respect to LSR velocity.

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thumbnail Fig. A.3

Models (blue) and observed data (black) of M stars, plotted with respect to LSR velocity. An * next to the telescope name indicates archival data is plotted.

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thumbnail Fig. A.4

Goodness of fit as defined by model/observed intensity for C stars.

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thumbnail Fig. A.5

Goodness of fit as defined by model/observed intensity for S stars.

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thumbnail Fig. A.6

Goodness of fit as defined by model/observed intensity for M stars.

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As well as plotting the model and observed CO lines, we have calculated “goodness of fit” per line in each star. This gives us an indication of which lines may be outliers or whether there are any trends across lines.

Goodness of fit for C stars is shown in Fig. A.4, for S stars in Fig. A.5, and for M stars in Fig. A.6. See Fig. 5 and Sect. 4.2 for a discussion of goodness of fit across the entire sample. A list of archival lines included in our models is given in Table C.1.

Appendix B: New observations

Appendix B.1: CO lines

Of the data described in Table 2, those stars for which we ran radiative transfer models were plotted in the body of the paper and in Appendix A. The remaining lines, which were excluded from modelling for various reasons (see discussion in Sect. 4.1) are now presented here. The C stars are plotted in Fig. B.1, the S stars are plotted in Fig. B.2 and the M stars are plotted in Fig. B.3.

In particular, the unusual line profile due to the presence of a detached shell can be seen in the C star R Scl and double-component winds are clearly evident in C star TX Psc and S stars RS Cnc and π1 Gru.

The observation identifiers (ObsIDs) for our Herschel observations are listed in Table B.1.

Appendix B.2: Bonus lines

As mentioned in Sect. 2.4, we acquired some “bonus” line spectra for molecules that were observable within our target frequency ranges. In HIFI, in the same range as the CO (5 → 4) line, we detected SiO (13 → 12) at 564.249 GHz. As can be seen in Table B.2, it was mostly detected in M stars, especially those of lower mass-loss rates, which is in agreement with the trend found by González Delgado et al. (2003) and the calculations performed by Schöier et al. (2004).

Our detections are plotted in Fig. B.4. There was one detection in an S star, RS Cnc, which is the most “M-like” S star in our sample, based on optical classifications. There were also two detections in C stars: V384 Per and V821 Her. They both have mass-loss rates in the range ~2–3 × 10-6 M yr-1, putting them in the mid-to-high mass-loss rate range. They are located at 560 and 600 pc respectively, making them two of the nearest C stars in the higher mass-loss rate range (>10-6 M yr-1). This could be why they had (weak) detections, while there were no detections in other C stars. The two C stars are among the sample modelled in SiO by Schöier et al. (2006). These authors used observations of SiO lines from J = 8 → 7 down to J = 2 → 1 and there are six overlapping stars between their sample and the one in this paper, leaving four stars (AI Vol, II Lup, RV Aqr, and R Lep) detected in the lower-J SiO lines but not in the higher-J HIFI line.

Covered by our IRAM observations was the 13CO (1 → 0) line at 110.201 GHz. The integrated intensities for these detections are given in Table B.2 and the observations are plotted in Fig. B.5. The 13CO (1 → 0) line seems to have been most reliably detected in higher mass-loss rate sources across the three

chemical types. It was not detected at all in stars with mass-loss rates ~10-8–10 (note, however, that we are only dealing with two stars in this range) and was detected increasingly often for increasing mass-loss rates across chemical types.

The SiS (6 → 5) line at 108.924 GHz was also detected in seven C stars, five M stars and no S stars. The integrated intensities are listed in Table B.2 and the spectra are plotted in Fig. B.6. The C stars with detections were all in the mass-loss rate range ~10-6 to 10-5 M yr-1, with no detections for lower mass-loss rate objects and only one detection out of the two highest mass-loss rate C stars observed. Of the M stars, SiS was also detected in the higher mass-loss rate objects, but not in the highest mass-loss rate star, V1111 Oph. This trend suggests that SiS is more readily formed – or at least more readily detectable – in sources of intermediate mass-loss rate, around the range ~10-6 to 10-5 M yr-1.

CN lines were covered by both HIFI and IRAM observations. The CN (59/2 → 47/2) and (511/2 → 49/2) line groups with rest frequencies taken as 566.693 GHz and 566.947 GHz were covered in the observing range for CO (5 → 4) and were detected in a handful of C stars. Our IRAM observations covered the CN N = 1 → 0 lines at 113.123 GHz and 113.488 GHz for the (11/2 − 01/2) and (13/2 − 01/2) line groups, respectively, and the CN N = 2 → 1 lines at 226.617 GHz, 226.874 GHz and 226.360 GHz for the (23/2 − 11/2), (23/2 − 13/2), and (25/2 − 13/2) line groups, respectively. The hyperfine structure of the low-N CN lines can be seen particularly clearly. The integrated intensities of each line group are given in Table B.3 and the observations themselves are plotted in Fig. B.7.

Low-N CN lines were detected in all of the observed C stars. Not all lines were detected in all stars, however. The lowest mass-loss rate star, U Hya, did not yield a clear detection of the (11/2 − 01/2) or (23/2 − 13/2) groups, although the remaining lines, including the (59/2 → 47/2) and (511/2 → 49/2) groups were clearly seen. The (23/2 − 13/2) was also not detected in V701 Cas, V1259 Ori, V688 Mon, or V821 Her, all of which are relatively high mass-loss rate objects with ~ 10-6 − 10-5 M yr-1. One S star, S Cas, was also detected in CN, in the (13/2 − 01/2), (23/2 − 11/2), (23/2 − 13/2), and (25/2 − 13/2) line groups. S Cas is the highest mass-loss rate and expansion velocity S star and, from its optical classification of S4/6e, is on the higher C/O end of the S star scale.

The last bonus line we detected was HC3N (12 → 11) at 109.174 GHz. The integrated intensities for the detections are listed in Table B.3 and the spectra are plotted in Fig. B.6. HC3N was only detected in C stars and not in the three lowest mass-loss rate objects with mass-loss rates below 10-6 M yr-1. This is probably due to a higher density of available carbon to form this (simple) carbon-chain molecule in the higher mass-loss rate C stars.

thumbnail Fig. B.1

New data from HIFI and IRAM for C stars not modelled in this paper, plotted with respect to LSR velocity.

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thumbnail Fig. B.2

New data from HIFI and IRAM for S stars not modelled in this paper, plotted with respect to LSR velocity.

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thumbnail Fig. B.3

New data from HIFI and IRAM for M stars not modelled in this paper, plotted with respect to LSR velocity.

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thumbnail Fig. B.4

New SiO data from HIFI, plotted with respect to LSR velocity.

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thumbnail Fig. B.5

New 13CO data from IRAM, plotted with respect to LSR velocity.

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thumbnail Fig. B.6

New SiS and HC3N data from IRAM, plotted with respect to LSR velocity. Note that the peak at ~–80 km s-1 in the GY Cam H3CN spectrum is an artefact and not part of the H3CN line.

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thumbnail Fig. B.7

New CN data from HIFI and IRAM, plotted with respect to LSR velocity of the reddest component. In the case of the HIFI lines, both the (59/2 → 47/2) and (511/2 → 49/2) lines are plotted together at the rest frequency of the former.

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Table B.1

ObsIDs for Herschel observations.

Table B.2

IRAM and HIFI 13CO, SiO and SiS line observations.

Table B.3

HIFI and IRAM CN and H3CN line group observations.

Appendix C: Supplementary line data

As discussed in Sect. 2.3, we included substantial archival data in our modelling procedure to find the models which best fit the

widest range of data possible. The archival data we used to constrain our models is listed in Table C.1.

Table C.1

Archival data of other CO observations of the stars used in our modelling.


© ESO, 2015

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