Issue |
A&A
Volume 434, Number 1, April IV 2005
|
|
---|---|---|
Page(s) | 257 - 274 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20034114 | |
Published online | 01 April 2005 |
The circumstellar environments of high-mass protostellar objects
II. Dust continuum models
1
School of Physics and Astronomy, The University of Manchester, Sackville Street, PO Box 88, Manchester, M60 1QD, UK e-mail: G.Fuller@manchester.ac.uk
2
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138, USA
Received:
24
July
2003
Accepted:
10
January
2005
We analyse the dust continuum emission seen towards a sample of
candidate high-mass protostellar objects, modelling the cores we recently
observed at 850 μm with a one-dimensional radiative transfer code.
Fitting radial slices in a range of directions across sources, we identify a
number of objects that have non-spherical density profiles and show that for
such sources fitting the azimuthal averaged emission produces erroneous
estimates of the source properties. We find the majority of cores can be
successfully modelled using envelopes of power-law density structure (where
), finding a mean power-law index of
. These envelopes extend considerably further, are
more dense, and have a more shallow density profile than those bearing
low-mass protostars. The majority of best-fit models have a SED resembling
the cold-component dust bodies previously proposed for the sample, implying
the short wavelength emission seen towards the HMPOs either originates from
a separate hot dust component(s), or involves mechanisms such as accretion
disks, stochastic heating and/or optically thin cavities not included in the
radiative transfer model. We find evidence of smaller dust-free cavities
towards some pre-UCHII sources. The modelling indicates a correlation
between α and optical depth, suggesting that the densest cores also
tend to have the most strongly peaked power-law density profiles.
Key words: stars: formation / stars: circumstellar matter / ISM: clouds / ISM: dust, extinction
© ESO, 2005
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