Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-01-31
Astrophys.J.537:283-303,2000
Astronomy and Astrophysics
Astrophysics
To be published in The Astrophysical Journal. 54 pages including 14 figures Revised version with references added
Scientific paper
10.1086/309011
The physical structure of the envelopes around a sample of fourteen massive (1000-100,000 solar L) young stars is investigated on 100- 100,000 AU scales using maps and spectra in submillimeter continuum and lines of C17O, CS and H2CO. The total column densities and the temperature profiles are obtained by fitting self-consistent dust models to submillimeter photometry. Both the molecular line and dust emission data indicate density gradients ~r^{-alpha}, with alpha=1.0-1.5, significantly flatter than the alpha=2.0 generally found for low-mass objects. This flattening may indicate that in massive young stellar objects, nonthermal pressure is more important for the support against gravitational collapse, while thermal pressure dominates for low-mass sources. We find alpha=2 for two hot core-type sources, but regard this as an upper limit since in these objects, the CS abundance may be enhanced in the warm gas close to the star.
Blake Geoffrey A.
der Tak Floris F. S. van
Evans Neal J.
van Dishoeck Ewine F.
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