Volume 453, Number 3, July III 2006
|Page(s)||1003 - 1026|
|Section||Interstellar and circumstellar matter|
|Published online||28 June 2006|
A SCUBA imaging survey of ultracompact HII regions
The environments of massive star formation
Centre for Astrophysics Research, Science & Technology Research Institute, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK e-mail: email@example.com
2 Centre for Astrophysics & Planetary Science, School of Physical Sciences, University of Kent, Canterbury CT2 7NR, UK
3 School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
4 School of Physics, University of New South Wales, NSW, 2052, Australia
5 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, PO Box 88, Manchester, M60 1QD, UK
6 School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UK
Accepted: 28 March 2006
We present a SCUBA submillimetre (450 and 850 μm) survey of the environment of 105 IRAS point sources, selected from the Wood & Churchwell (1989a) and Kurtz et al. (1994) radio ultracompact (UC) Hii region surveys. We detected a total of 155 sub-mm clumps associated with the IRAS point sources and identified three distinct types of object: ultracompact cm-wave sources that are not associated with any sub-mm emission (sub-mm quiet objects), sub-mm clumps that are associated with ultracompact cm-wave sources (radio-loud clumps); and sub-mm clumps that are not associated with any known ultracompact cm-wave sources (radio-quiet clumps). 90% of the sample of IRAS point sources were found to be associated with strong sub-mm emission. We consider the sub-mm colours, morphologies and distance-scaled fluxes of the sample of sub-mm clumps and show that the sub-mm quiet objects are unlikely to represent embedded UC Hii regions unless they are located at large heliocentric distances. Many of the 25 SCUBA fields contain more than one sub-mm clump, with an average number of companions (the companion clump fraction) of 0.90. The clumps are more strongly clustered than other candidate HMPOs and the mean clump surface density exhibits a broken power-law distribution with a break at 3 pc. We demonstrate that the sub-mm and cm-wave fluxes of the majority of radio-loud clumps are in excellent agreement with the standard model of ultracompact Hii regions. We speculate on the nature of the radio-quiet sub-mm clumps and, whilst we do not yet have sufficient data to conclude that they are in a pre-UC Hii region phase, we argue that their characteristics are suggestive of such a stage.
Key words: stars: formation / ISM: HII regions / ISM: dust, extinction / submillimeter / radio continuum: ISM
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.