Furness, J.P., Crowther, P.A., Morris, P.W. et al. (4 more authors) (2010) Mid-infrared diagnostics of metal-rich H ii regions from VLT and Spitzer spectroscopy of young massive stars in W31 star. Monthly Notices of the Royal Astronomical Society , 403 (3). pp. 1433-1447. ISSN 0035-8711
Abstract
We present near-infrared Very Large Telescope/Infrared Spectrograph and Array Camera and mid-infrared (mid-IR) Spitzer/Infrared Spectrograph spectroscopy of the young massive cluster in the W31 star-forming region. H-band spectroscopy provides refined classifications for four cluster member O stars with respect to Blum et al. In addition, photospheric features are detected in the massive young stellar object (massive YSO) #26. Spectroscopy permits estimates of stellar temperatures and masses, from which a cluster age of ∼0.6 Myr and distance of 3.3 kpc are obtained, in excellent agreement with Blum et al. IRS spectroscopy reveals mid-IR fine structure line fluxes of [Ne II–III] and [S III–IV] for four O stars and five massive YSOs. In common with previous studies, stellar temperatures of individual stars are severely underestimated from the observed ratios of fine-structure lines, despite the use of contemporary stellar atmosphere and photoionization models. We construct empirical temperature calibrations based upon the W31 cluster stars of known spectral type, supplemented by two inner Milky Way ultracompact (UC) H II regions whose ionizing star properties are established. Calibrations involving [Ne III] 15.5 μm/[Ne II] 12.8 μm, [S IV] 10.5 μm/[Ne II] 12.8 μm or [Ar III] 9.0 μm/[Ne II] 12.8 μm have application in deducing the spectral types of early to mid O stars for other inner Milky Way compact and UC H II regions. Finally, evolutionary phases and time-scales for the massive stellar content in W31 are discussed, due to the presence of numerous young massive stars at different formation phases in a ‘coeval’ cluster.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2010 The Authors. Journal compilation © 2010 RAS Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords: | stars: early-type; stars: fundamental parameters; H ii regions; open clusters and associations: individual: W31 (G10; 2-0; 3); infrared: ISM; COMPACT HII-REGIONS; RADIO RECOMBINATION LINES; GALACTIC-O-STARS; STARBURST GALAXIES; ISO SPECTROSCOPY; SPACE-TELESCOPE; STELLAR CONTENT; ORION NEBULA; IONIZING-RADIATION; INFRARED GALAXIES |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 06 Nov 2017 15:59 |
Last Modified: | 06 Nov 2017 15:59 |
Published Version: | https://doi.org/10.1111/j.1365-2966.2010.16206.x |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1111/j.1365-2966.2010.16206.x |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:123562 |