Massive Stellar Content of Giant H II Regions in M33 and M101
Abstract
Far-ultraviolet (900-1200 Å) spectral synthesis of nine giant extragalactic H II regions in M33 and M101 is performed to study their massive stellar content. Several parameters are quantified, predicted, and compared to the literature: age, stellar mass, initial mass function (IMF) slope, number of O-type and Wolf-Rayet stars, and Hα and 5500 Å continuum fluxes. The results of this particular technique are consistent with other methods and observations. This work shows that a total stellar mass of a few 103 Msolar is needed to populate the IMF bins well enough at high masses to obtain accurate results from the spectral synthesis technique in the far-ultraviolet. A flat IMF slope seems to characterize better the stellar line profiles of these objects, which is likely the first sign of a small number statistics effect on the IMF. Finally, the H II region NGC 5461 is identified as a good candidate for hosting a second generation of stars, not yet seen at far-ultraviolet wavelengths.
Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by The Johns Hopkins University under NASA contract NAS5-32985.- Publication:
-
The Astronomical Journal
- Pub Date:
- February 2006
- DOI:
- 10.1086/499073
- arXiv:
- arXiv:astro-ph/0510686
- Bibcode:
- 2006AJ....131..849P
- Keywords:
-
- Galaxies: Individual: Messier Number: M33;
- Galaxies: Individual: Messier Number: M101;
- Galaxies: Stellar Content;
- Stars: Early-Type;
- Ultraviolet: Stars;
- Astrophysics
- E-Print:
- 13 pages including figures, accepted for publication in AJ