The Red MSX Source survey: the bolometric fluxes and luminosity distributions of young massive stars^⋆

¹ Department of Physics and AstronomyUniversity of Exeter, Exeter, Devon EX4 4QL, UK
e-mail: joe@astro.ex.ac.uk
² School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
³ Australia Telescope National Facility, CSIRO Astronomy and Space Science, Sydney, NSW 2052, Australia
⁴ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
⁵ Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
⁶ Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623, USA

Received: 22 March 2010
Accepted: 6 September 2010

Abstract

Context. The Red MSX Source (RMS) survey is returning a large sample of massive young stellar objects (MYSOs) and ultra-compact (UC) H ii regions using follow-up observations of colour-selected candidates from the MSX point source catalogue.

Aims. We obtain the bolometric fluxes and, using kinematic distance information, the luminosities for young RMS sources with far-infrared fluxes.

Methods. We use a model spectral energy distribution (SED) fitter to obtain the bolometric flux for our sources, given flux data from our work and the literature. The inputs to the model fitter were optimised by a series of investigations designed to reveal the effect varying these inputs had on the resulting bolometric flux. Kinematic distances derived from molecular line observations were then used to calculate the luminosity of each source.

Results. Bolometric fluxes are obtained for 1173 young RMS sources, of which 1069 have uniquely constrained kinematic distances and good SED fits. A comparison of the bolometric fluxes obtained using SED fitting with trapezium rule integration and two component greybody fits was also undertaken, and showed that both produce considerable scatter compared to the method used here.

Conclusions. The bolometric flux results allowed us to obtain the luminosity distributions of YSOs and UCH ii regions in the RMS sample, which we find to be different. We also find that there are few MYSOs with L ≥ 10⁵ L_⊙, despite finding many MYSOs with 10⁴ L_⊙  ≥ L ≥ 10⁵ L_⊙.