Issue |
A&A
Volume 417, Number 1, April I 2004
|
|
---|---|---|
Page(s) | 115 - 133 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20031733 | |
Published online | 16 March 2004 |
The circumstellar environments of high-mass protostellar objects
I. Submillimetre continuum emission
1
Department of Physics, UMIST, PO Box 88, Manchester, M60 1QD, UK
2
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138, USA
Corresponding author: G. A. Fuller, g.fuller@umist.ac.uk
Received:
27
March
2003
Accepted:
3
December
2003
We present maps of the 850 μm and 450 μm continuum emission
seen towards a sample of 68 high-mass protostellar candidates with
luminosities ranging from 10 to
. Most of these candidate high-mass stars are in the earliest
stages of evolution, and have not yet developed an ultra-compact HII region.
We observe a variety of continuum emission morphologies, from compact
symmetric sources through to multiple cores embedded in long filaments of
emission. We find on average there is a 65% probability of an IRAS
point-source having a companion detection at submillimetre wavelengths. The
ratio of integrated flux to peak flux for our detections shows no strong
dependence on distance, suggesting the emission we have observed is
primarily from scale-free envelopes with power-law density structures.
Assuming a near kinematic distance projection, the clumps we detect vary in
mass from
to over 1000
, with a mean clump
mass of 330
, column density of
cm-2 and
diameter of
pc. The high luminosity and low mass of the smallest
clumps suggests they are accompanied by a minimal number of stellar
companions, while the most massive clumps may be examples of young
protogroups and protoclusters. We measure the spectral index of the dust
emission (α) and the spectral index of the dust grain opacity
(β) towards each object, finding clumps with morphologies suggestive
of strong temperature gradients, and of grain growth in their dense inner
regions. We find a mean value for β of 0.9, significantly smaller
than observed towards UCHII regions.
Key words: stars: formation / stars: circumstellar matter / ISM: clouds / ISM: dust, extinction
© ESO, 2004
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