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On the massive star content of the nearby dwarf irregular Wolf-Rayet galaxy IC 4662

Crowther, P.A. and Bibby, J.L. (2009) On the massive star content of the nearby dwarf irregular Wolf-Rayet galaxy IC 4662. Astronomy and Astrophysics. ISSN 0004-6361

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Abstract

Aims. We investigate the massive stellar content of the nearby dwarf irregular Wolf-Rayet galaxy IC 4662, and consider its global star forming properties in the context of other metal-poor galaxies, the SMC, IC 10 and NGC 1569.

Methods. Very Large Telescope/FORS2 imaging and spectroscopy plus archival Hubble Space Telescope/ACS imaging datasets permit us to spatially identify the location, number and probable subtypes of Wolf-Rayet stars within this galaxy. We also investigate suggestions that a significant fraction of the ionizing photons of the two giant H II regions A1 and A2 lie deeply embedded within these regions.

Results. Wolf-Rayet stars are associated with a number of sources within IC 4662-A1 and A2, plus a third compact H II region to the north west of A1 (A1-NW). Several sources appear to be isolated, single (or binary) luminous nitrogen sequence WR stars, while extended sources are clusters whose masses exceed the Orion Nebula Cluster by, at most, a factor of two. IC 4662 lacks optically visible young massive, compact clusters that are common in other nearby dwarf irregular galaxies. A comparison between radio and H-derived ionizing fluxes of A1 and A2 suggests that 30–50% of their total Lyman continuum fluxes lie deeply embedded within these regions.

Conclusions. The star formation surface density of IC 4662 is insufficient for this galaxy to qualify as a starburst galaxy, based upon its photometric radius, R25. If instead, we were to adopt the V

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 EDP Sciences. Reproduced in accordance with the publisher's self-archiving policy
Keywords: galaxies: individual: IC 4662 – stars: Wolf-Rayet – (ISM): HII regions – galaxies: star clusters – galaxies: starburst – galaxies: dwarf
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 27 May 2009 16:33
Last Modified: 13 Jun 2014 11:46
Published Version: http://dx.doi.org/10.1051/0004-6361/200911758
Status: Published
Publisher: EDP Sciences
Refereed: Yes
Identification Number: 10.1051/0004-6361/200911758
URI: http://eprints.whiterose.ac.uk/id/eprint/8609

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