The Wolf-Rayet Content of Local Group Galaxies
Abstract
The physics behind hot, massive stars is complicated, making the stars' evolution difficult to model. For this reason, we rely on observational tests to see how well stellar evolutionary theory predicts the relative numbers of various types of massive stars. The star-forming galaxies of the Local Group, with their varying metallicities, provide an excellent laboratory for such studies, as massive star evolution is strongly influenced by mass-loss rates, which in turn depend upon metallicity, at least on the main sequence. We've recently begun a far deeper, and more complete survey of the Wolf-Rayet (WR) content of Local Group galaxies compared to what has been done in the past. Using narrow-band interference filter imaging and following up with spectroscopy has allowed us to determine the number of WR stars in both M31 and M33 to ~ 5%. Given our previous knowledge of the WR content of the SMC and LMC, we can now examine how the relative number of WC-type and WN-type WRs varies with metallicity over a range of 10. Here we will present our current results as well as the follow-up work we are doing investigating the relative binary frequency of WRs in M31 and M33 to see if the unexpectedly large fraction of WCs in M31 are a product of binary evolution
- Publication:
-
Massive Stars: From alpha to Omega
- Pub Date:
- June 2013
- Bibcode:
- 2013msao.confE.128N