EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 507/2 Article
Free access article

Issue A&A
Volume 507, Number 2, November IV 2009
Page(s) 795 - 802
Section Galactic structure, stellar clusters, and populations
DOI http://dx.doi.org/10.1051/0004-6361/200912608
Published online 15 September 2009

A&A 507, 795-802 (2009)
DOI: 10.1051/0004-6361/200912608

The RMS survey

H $\mathsf{_2}$O masers towards a sample of southern hemisphere massive YSO candidates and ultra compact HII regions
J. S. Urquhart1, 2, M. G. Hoare1, S. L. Lumsden1, R. D. Oudmaijer1, T. J. T. Moore3, P. R. Brook1, J. C. Mottram1, 4, B. Davies1, and J. J. Stead1

1  School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
2  Australia Telescope National Facility, CSIRO, Sydney, NSW 2052, Australia
    e-mail: james.urquhart@csiro.au
3  Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead, CH41 1LD, UK
4  School of Physics, University of Exeter, Exeter, EX7 4QL, UK

Received 1 June 2009 / Accepted 25 August 2009

Abstract
Context. The red MSX source (RMS) survey has identified a large sample of candidate massive young stellar objects (MYSOs) and ultra compact (UC) HII regions from a sample of ~2000 MSX and 2MASS colour selected sources.
Aims. To search for H2O masers towards a large sample of young high mass stars and to investigate the statistical correlation of H2O masers with the earliest stages of massive star formation.
Methods. We have used the Mopra Radio telescope to make position-switched observations towards ~500 UCHII regions and MYSOs candidates identified from the RMS survey and located between 190° < l < 30°. These observations have a 4$\sigma$ sensitivity of ~1 Jy and a velocity resolution of ~0.4 km s-1.
Results. We have detected 161 H2O masers, approximately 75% of which were previously unknown. Comparing the maser velocities with the velocities of the RMS sources, determined from 13CO observations, we have identified 135 RMS-H2O maser associations, which corresponds to a detection rate of ~27%. Taking into account the differences in sensitivity and source selection we find our detection rate is in general agreement with previously reported surveys.
Conclusions. We find similar detection rates for UCHII regions and MYSOs candidates, suggesting that the conditions needed for maser activity are equally likely in these two stages of the star formation process. Looking at the detection rate as a function of distance from the Galactic centre we find it significantly enhanced within the solar circle, peaking at ~37% between 6–7 kpc, which is consistent with previous surveys of UC HII regions, possibly indicating the presence of a high proportion of more luminous YSOs and HII regions.


Key words: stars: formation -- stars: early-type -- stars: pre-main sequence



© ESO 2009


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.