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# The RMS survey: The luminosity functions and timescales of massive young stellar objects and compact H II regions

Mottram, Joseph C., Hoare, Melvin G., Davies, Ben, Lumsden, Stuart L., Oudmaijer, Rene D., Urquhart, J.S., Moore, Toby J.T., Cooper, Heather D.B., Stead, Joseph J. (2011) The RMS survey: The luminosity functions and timescales of massive young stellar objects and compact H II regions. Astrophysical Journal Letters, 730 (2). p. 33. ISSN 2041-8205. (doi:10.1088/2041-8205/730/2/L33) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:52225)

 The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. Official URLhttp://www.dx.doi.org/10.1088/2041-8205/730/2/L33

## Abstract

We present a determination of the luminosity functions of massive young stellar objects (MYSOs) and compact (C) H II regions within the Milky Way using the large, well-selected sample of these sources identified by the Red MSX Source survey. The MYSO luminosity function decreases monotonically such that there are few with Lgsim105 L ?, while the CH II regions are detected up to ~106 L ?. The lifetimes of these phases are also calculated as a function of luminosity by comparison with the luminosity function for local main-sequence OB stars. These indicate that the MYSO phase has a duration ranging from 4×105 yr for 104 L ? to ~7×104 yr at 105 L ?, while the CH II region phase lasts of order 3×105 yr or ~3%-10% of the exciting star's main-sequence lifetime. MYSOs between 104 L ? and ~105 L ? are massive but do not display the radio continuum or near-IR H I recombination line emission indicative of an H II region, consistent with being swollen due to high ongoing or recent accretion rates. Above ~105 L ? the MYSO phase lifetime becomes comparable to the main-sequence Kelvin-Helmholtz timescale, at which point the central star can rapidly contract onto the main sequence even if still accreting, and ionize a CH II region, thus explaining why few highly luminous MYSOs are observed.

Item Type: Article 10.1088/2041-8205/730/2/L33 Galaxy: stellar content, Hii regions, stars: early-type, stars: formation, stars: luminosity function: mass function, surveys Q Science > QB Astronomy > QB460 Astrophysics Divisions > Division of Natural Sciences > Physics and Astronomy James Urquhart 30 Nov 2015 16:04 UTC 16 Nov 2021 10:21 UTC https://kar.kent.ac.uk/id/eprint/52225 (The current URI for this page, for reference purposes) https://orcid.org/0000-0002-1605-8050
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