Astronomy & Astrophysics

All Figures

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig1.eps}} \end{figure}$ Figure 1: Histograms of sources at 6.7 $\mu$ m ( left) and 14.3 $\mu$ m ( right) for the CW field ( upper) and the total sample ( lower). The boldface steps in the lower panels correspond to the population of mid-IR excess sources. The expected number of galactic sources in each bin, normalised to each field, from modelling the stellar content in a cone along the line-of-sight is inserted for zero cloud extinction (solid lines), $A_{\rm V} \approx 5$ (dotted lines), and $A_{\rm V} \approx 10$ (dashed lines).
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig2.eps}} \end{figure}$ Figure 2: The colour index [14.3/6.7] defined as $\log~ (F_{\nu}^{14.3}/F_{\nu}^{6.7})$ is shown on the y-axis and the flux $F_{\nu }^{14.3}$ also given in magnitudes m₁₄ is shown on the x-axis. The SED index between 6.7 and 14.3 $\mu$ m is given on the right hand y-axis. 53 sources with substantial IR excess are located above [14.3/6.7] = -0.2 or $\alpha _{\rm IR}^{7-14} = -1.6$ (dotted line). While 28 of these were previously suggested as YSOs, 25 are new YSO candidates (filled circles).
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig3.eps}} \end{figure}$ Figure 3: The $H-K/K-m_{\rm 6.7}$ diagram of the Serpens Cloud Core with individual error bars for each source, and some H upper limits (arrows). The IR excess sources from Fig. 2 are encircled. The intrinsic colours of main-sequence (bold solid), giants (bold dotted), and supergiant (bold dashed) stars cluster close to (0, 0). A reddening vector (solid line) is estimated on the basis of the four sources without [14.3/6.7] excess (triangles). Eight additional IR excess YSOs (numbered) were found in this diagram, i.e. displaced by more than $1\sigma$ to the right of the reddening band (dotted vector).
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig4.eps}} \end{figure}$ Figure 4: Arnica K band mapping of the region to the NW of the JHK field. ISOCAM sources are encircled and their identifications given. Sources 159, 202, 216 and EC38 are YSOs with [14.3/6.7] colour excess. Sources SVS9 and 209 are without such an excess. The remaining sources are not detected at 14.3 $\mu$ m. See Appendix A.
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig5.eps}} \end{figure}$ Figure 5: The spectral index $\alpha _{\rm IR}^{2-7}$ versus $\alpha _{\rm IR}^{2-14}$ , or equivalently, the K-m₇/K-m₁₄ colour diagram, for a subset of the ISOCAM sample. The locations of Class I, Class II and Class III sources and field stars are indicated. Note the relatively large fraction of Class I sources in this diagram.
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig6.eps}} \end{figure}$ Figure 6: SEDs of HB1 and EC129. The flux points at 25, 60 and 100 $\mu$ m are taken from Hurt & Barsony (1996). Note that the 60 and 100 $\mu$ m points for EC129 are upper limits only.
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig7.eps}} \end{figure}$ Figure 7: The average flux at 6.7 and 14.3 $\mu$ m versus $\alpha _{\rm IR}^{2-14}$ for a subset of the ISOCAM sample. The location of Class I, Class II and Class III sources and field stars are indicated. Filled circles mark the 15 YSOs with $\alpha _{\rm IR}^{2-14} > 0$ and $\alpha _{\rm IR}^{7-14} < 0$ .
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig8.eps}} \end{figure}$ Figure 8: The 6.7 $\mu$ m luminosity function for the sample of Class Is and flat-spectrum sources ( lower) and Class II sources ( upper).
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig9.eps}} \end{figure}$ Figure 9: Synthetic LFs were calculated for 4 different ages of a coeval population on the basis of pre-main sequence tracks of D'Antona & Mazzitelli (1998) and 3 different underlying IMFs. The number of sources per bin is plotted vs. $\log L$ , and the synthetic LFs are plotted over the observed LF for the Class II sources in Serpens (histogram). Both the Scalo (1998) three-segment power-law IMF (solid) and the Kroupa et al. (1993) three-segment power-law IMF (dashed) seem plausible for a coeval population of $\sim$ 2 Myr all the way down to the estimated completeness limit at $L \sim 0.08~ L_{\odot}$ (dotted vertical line). The observed LF is also consistent with the Salpeter IMF (dashed-dotted) for this age at the high luminosity end (it has been extrapolated to low masses for reference only).
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{15.1cm}{!}{\includegraphics[clip]{0775fg10.eps}} \end{figure}$ Figure 10: Spatial distribution of the ISOCAM sources in the Serpens Cloud. Sources with mid-IR excesses (filled circles) are seen to cluster strongly in the Cloud Core (field CE), while the CW field contains almost exclusively sources without mid-IR excesses (open circles). Indicated are also sources with 6.7 $\mu$ m detections only (plus signs) and 14.3 $\mu$ m detections only (crosses). The coordinates have epoch J2000. Each of the 3 separate ISOCAM rasters, CE, CW, and CS are indicated, and the small box outlines the region where deep JHK imaging is available (Kaas 1999a).
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{14.4cm}{!}{\rotatebox{0}{\includegraphics[clip]{0775fg11.ps}}} \end{figure}$ Figure 11: Dust continuum mosaic (contours and greyscale) of the Serpens main core taken at 1.3 mm with the IRAM 30 m telescope and the MPIfR 37-channel bolometer array (MAMBO). Contour levels: 50. to 200 by 50, 300 to 1000. by 100. mJy/11 $^{\prime \prime }$ -beam; rms noise level: ${\sim } 17$ mJy/11 $^{\prime \prime }$ -beam. The Class 0 sources are indicated with names and arrows. The location of Class I sources (red circles), flat-spectrum sources (red crosses), and Class II sources (blue filled squares) demonstrates the strong clustering of protostar candidates along the dense filament.
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fg12.eps}} \end{figure}$ Figure 12: A K band image of the Serpens Cloud Core ( $6'~ \times ~8'$ ) from Kaas (1999a) with the Class Is (circles), flat-spectrum sources (squares) and Class IIs (hexagonals) marked. The "blue'' ISOCAM sources are marked with triangles. The ridge along SE-NW is well outlined by the Class I and flat-spectrum sources.
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.2cm}{!}{\rotatebox{270}{\includegraphics[clip]{0775fg13.ps}}} \end{figure}$ Figure 13: The distribution of source separations for Class I and flat-spectrum objects (circles) and Class II sources (dots). The number of separations between sources (per bin) is plotted on the y-axis as a function of separation in arc minutes on the x-axis. The chosen bin size was 6 times the minimum separation, translating to $46.1\hbox {$^{\prime \prime }$ }$ and $66.1\hbox {$^{\prime \prime }$ }$ for the protostar and Class II source samples, respectively.
Open with DEXTER

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fgA1.eps}} \end{figure}$ Figure A.1: The deep map D2 at 6.7 $\mu$ m ( left) and 14.3 $\mu$ m ( right). North up and East left.

In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig4.eps}} \end{figure}$	Figure 4: Arnica K band mapping of the region to the NW of the JHK field. ISOCAM sources are encircled and their identifications given. Sources 159, 202, 216 and EC38 are YSOs with [14.3/6.7] colour excess. Sources SVS9 and 209 are without such an excess. The remaining sources are not detected at 14.3 $\mu$ m. See Appendix A.
Open with DEXTER

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig5.eps}} \end{figure}$	Figure 5: The spectral index $\alpha _{\rm IR}^{2-7}$ versus $\alpha _{\rm IR}^{2-14}$ , or equivalently, the K-m₇/K-m₁₄ colour diagram, for a subset of the ISOCAM sample. The locations of Class I, Class II and Class III sources and field stars are indicated. Note the relatively large fraction of Class I sources in this diagram.
Open with DEXTER

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig6.eps}} \end{figure}$	Figure 6: SEDs of HB1 and EC129. The flux points at 25, 60 and 100 $\mu$ m are taken from Hurt & Barsony (1996). Note that the 60 and 100 $\mu$ m points for EC129 are upper limits only.
Open with DEXTER

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig7.eps}} \end{figure}$	Figure 7: The average flux at 6.7 and 14.3 $\mu$ m versus $\alpha _{\rm IR}^{2-14}$ for a subset of the ISOCAM sample. The location of Class I, Class II and Class III sources and field stars are indicated. Filled circles mark the 15 YSOs with $\alpha _{\rm IR}^{2-14} > 0$ and $\alpha _{\rm IR}^{7-14} < 0$ .
Open with DEXTER

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fig8.eps}} \end{figure}$	Figure 8: The 6.7 $\mu$ m luminosity function for the sample of Class Is and flat-spectrum sources ( lower) and Class II sources ( upper).
Open with DEXTER

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip]{0775fg12.eps}} \end{figure}$	Figure 12: A K band image of the Serpens Cloud Core ( $6'~ \times ~8'$ ) from Kaas (1999a) with the Class Is (circles), flat-spectrum sources (squares) and Class IIs (hexagonals) marked. The "blue'' ISOCAM sources are marked with triangles. The ridge along SE-NW is well outlined by the Class I and flat-spectrum sources.
Open with DEXTER