A Catalogue of Massive Young Stellar Objects

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Session 81 -- YSO's, Masers and Molecules
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[81.05] A Catalogue of Massive Young Stellar Objects

S.J. Chan, Th. Henning, K. Schreyer (Max Planck Society, Research Group ``Dust in Star-Forming Regions'')

\def\iras {{$IRAS~$}} \def\app {{$\approx~$}}

We report on an ongoing project to compile a catalogue of massive young stellar objects (YSOs). Massive young stellar objects are compact and luminous infrared sources. The stellar core is still surrounded by optically thick dust shells (cf. Henning 1990, Fundamentals of Cosmic Physics, 14, 321). This catalogue, which contains about 250 objects, will provide comprehensive information such as infrared and radio flux densities, association with maser sources, and outflow phenomena.

The objects were selected from the IRAS Point Source Catalogue based on the following criteria:

\noindent(1)~IRAS flux density qualities~$\geq$~2 in the 4 IRAS bands (12~$\mu$m, 25~$\mu$m, 60~$\mu$m and 100~$\mu$m).

\noindent(2)$~F_{\nu}(12~{\mu}m)~\le~F_{\nu}(25~{\mu}m)~\le~ F_{\nu}(60~{\mu}m)~\le~F_{\nu}(100~{\mu}m),\hfill\break F_{\nu}(100~{\mu}m)~\ge~1000~Jy$

\noindent(3)~IRAS colors (including uncertainty 0.15) should be within the following color box: -0.15~$\ge$~R(12/25)~$\ge$~1.15, -0.15~$\ge$~R(25/60)~$\ge$~0.75,\break -0.35~$\ge$~R(60/100)~$\ge$~0.35, where R(i/j)=j$F_\nu$(i)/i$F_\nu$(j)~ (Henning et al. 1990, A\&A, 227, 542)

\noindent(4) IRAS idtype~(type of objects)$\ne$~1; objects are not associated with galaxies or late-type stars; ~${\mid}$b${\mid}~\le$~ 10${^\circ}$

\noindent Our main goal is to collect the observational data of these sources as complete as possible. The flux densities from near-infrared to radio range are assembled (J, H, K bands, IRAS bands, 350~$\mu$m, 800~$\mu$m and 1.3~mm bands, 2~cm and 6~cm bands). The information on dust features (such as ice, silicate, PAH) comes from the IRAS Low Resolution Spectrometer Atlas and literature (cf. Volk \& Cohen, 1989, AJ, 98, 931). The maser sources (H$_2$O, type~I~OH, CH$_3$OH) and NH$_3$, HCO$^+$, and CS molecular line data towards these objects, which have been observed, are also reported. The CO outflow velocity will be given if the object is found to be associated with an outflow.

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