Astron. Astrophys. 361, 1095-1111 (2000)

7. Conclusion

We have presented observations of the infrared source RAFGL7009S taken in the millimetre and infrared wavelength range, allowing the determination of global source parameters such as:

• the bolometric luminosity of the source corresponds to a late O or early B star.

• the envelope mass is dominated by a high fraction of cold dust (21.8 to 43.4).

• the mean H₂ density is above 10⁶cm^-3 at the 10"  scale (0.1 pc).

The observations of different gas phase molecules in the millimetre range allow to probe various spatial and chemical aspect of the envelope. We determine:

• the position of the compact HII region, as probed with the hot core molecule CH₃CN. It is accurately determined with interferometer observations at arcsecond scales.

• The difference in size of the source as seen with CH₃CN, CH₃C₂H and CH₃OH. The latter two are more extended (a few arcseconds) and cooler than CH₃CN. Therefore they probe the interface between the extended envelope and the hot core region.

• D/H ratios in the gas phase for methanol (10^-2 210^-3) and water ( 2.510^-3). From the upper limits obtained on the solid observations ( 310^-2, 610^-3), we stress that the CH₃OD/CH₃OH ratio is a good tracer of the enrichment in D of ices when the methanol solid phase abundance can be estimated in the line of sight (which is the case for a few high mass protostars).

• we determine from HCN and HNC data, the existence along the line of sight of two velocity components with different kinetic temperatures. A cool component associated with the main velocity component ( 25K) and a warmer velocity component ( 40K) redshifted from the main cloud.

© European Southern Observatory (ESO) 2000

Online publication: October 10, 2000
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