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

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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[FORMULA]).

  • the mean H2 density is above 106cm-3 at the 10"  scale ([FORMULA]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 [FORMULA] [FORMULA][FORMULA]2[FORMULA]10-3) and water ([FORMULA] [FORMULA]2.5[FORMULA][FORMULA]10-3). From the upper limits obtained on the solid observations ([FORMULA] [FORMULA] 3[FORMULA]10-2, [FORMULA] [FORMULA] 6[FORMULA]10-3), 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 ([FORMULA] 25K) and a warmer velocity component ([FORMULA] 40K) redshifted from the main cloud.

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© European Southern Observatory (ESO) 2000

Online publication: October 10, 2000