Crowther, P.A. (2008) Wolf-Rayet Populations at High Metallicity. In: Israelian, G. and Meynet, G., (eds.) The Metal-Rich Universe. Cambridge Contemporary Astrophysics . Cambridge University Press , pp. 276-287. ISBN 9780521879989
Abstract
Observed properties of Wolf-Rayet stars at high metallicity are reviewed. Wolf-Rayet stars are more common at higher metallicity, as a result of stronger mass-loss during earlier evolutionary phases with late WC subtypes signatures of solar metallicity or higher. Similar numbers of early (WC4-7) and late (WC8-9) stars are observed in the Solar neighbourhood, whilst late subtypes dominate at higher metallicities, such as Westerlund 1 in the inner Milky Way and in M83. The observed trend to later WC subtype within metal-rich environments is intimately linked to a metallicity dependence of WR stars, in the sense that strong winds preferentially favour late subtypes. This has relevance to (a) the upper mass limit in metal-rich galaxies such as NGC 3049, due to softer ionizing fluxes from WR stars at high metallicity; (b) evolutionary models including a WR metallicity dependence provide a better match to the observed N(WC)/N(WN) ratio. The latter conclusion partially rests upon the assumption of constant line luminosities for WR stars, yet observations and theoretical atmospheric models reveal higher line fluxes at high metallicity.
Metadata
Item Type: | Book Section |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © Cambridge University Press 2008. This is an author produced version of a chapter subsequently published in The Metal-Rich Universe edited by Israelian, G and Meynet, G. This version is free to view and download for personal use only. Not for re-distribution, re-sale or use in derivative works. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | astro-ph; astro-ph |
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: | 25 Aug 2016 13:23 |
Last Modified: | 28 Mar 2018 20:50 |
Published Version: | http://www.cambridge.org/us/academic/subjects/astr... |
Status: | Published |
Publisher: | Cambridge University Press |
Series Name: | Cambridge Contemporary Astrophysics |
Refereed: | Yes |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:103978 |