EDP Sciences
Free access
Volume 366, Number 2, February I 2001
Page(s) L1 - L4
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20000571

A&A 366, L1-L4 (2001)
DOI: 10.1051/0004-6361:20000571

The WR content of IC10 - first detection of WC9 stars in a low metallicity environment?

P. Royer1, S. J. Smartt2, J. Manfroid1 and J.-M. Vreux1

1  Institut d'Astrophysique, Université de Liège, 5 avenue de Cointe, 4000 Liège, Belgium
2  Institute of Astronomy, University of Cambridge, Madingley Road, CB3 O4A Cambridge, UK

(Received 27 November 2000 / Accepted 12 December 2000)

We present deep, narrow-band photometry of the Local Group starburst galaxy IC 10. Our dedicated photometric system provides detection of 13 new Wolf-Rayet (WR) stars and allows spectral subtypes to be assigned. Three of these new stars appear to be WC9 subtypes. If confirmed, these would be the very first WC9 stars ever detected in a low metallicity environment, hence putting strong new constraints on the formation and evolution models of massive stars. Eight of the new WR stars are of the WC subtype, which does not significantly modify the anomalously high WC/WN ratio in IC 10. However it is likely that a number of Wolf-Rayet stars of the WNE and WC spectral subtypes are still to be discovered in the heart of the galaxy.

Key words: stars: Wolf-Rayet -- photometry: narrow bands -- galaxies: starburst, Local Group

Offprint request: P. Royer, proyer@ulg.ac.be

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