Wolf-Rayet Stars in IC 10: Probing the Nearest Starburst
Abstract
IC 10 is the nearest starburst galaxy, as revealed both by its Hα surface brightness and by the large number of Wolf-Rayet (W-R) stars per unit area. The relative number of known WC- to WN-type W-R stars has been thought to be unusually high (approximately two), which is unexpected for IC 10's metallicity. In this Letter, we report the first results of a new and deeper survey for W-R stars in IC 10. We successfully detected all of the spectroscopically known W-R stars, and based on comparisons with a neighboring control field, we estimate that the total number of W-R stars in IC 10 is about 100. We present spectroscopic confirmation of two of our W-R candidates, both of which are of WN type. Our photometric survey predicts that the actual WC/WN ratio is ~0.3. This makes the WC/WN ratio of IC 10 consistent with that expected for its metallicity but greatly increases the already unusually high number of W-R stars, resulting in a surface density that is about 20 times higher than in the LMC. If the majority of these candidates are spectroscopically confirmed, IC 10 must have an exceptional population of high-mass stars. Observations reported here were obtained at (1) the Multiple Mirror Telescope Observatory, a joint facility of the University of Arizona and the Smithsonian Institution, and at (2) the Kitt Peak National Observatory, a division of the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2002
- DOI:
- 10.1086/345405
- arXiv:
- arXiv:astro-ph/0210119
- Bibcode:
- 2002ApJ...580L..35M
- Keywords:
-
- Galaxies: Individual: Alphanumeric: IC 10;
- Galaxies: Starburst;
- Galaxies: Stellar Content;
- Stars: Evolution;
- Stars: Wolf-Rayet;
- Astrophysics
- E-Print:
- Accepted by ApJL