A survey of H-alpha emission in normal galaxies.
Abstract
The combined results of photometric and spectrophotometric surveys of H-alpha emission in 200 field and Virgo cluster galaxies are presented. In most spiral galaxies the emission is dominated by normal disk H II regions, and consequently the integrated Balmer flux of a galaxy can be used as a quantitative index of its current OB star formation rate. Uncertainties due to instrumental effects, nuclear emission, forbidden-line N II emission, and extinction by dust, are evaluated. The integrated emission of a galaxy is strongly correlated with its Hubble type and color, confirming the earlier conclusions of Cohen (1976). Emission among galaxies of a given type varies greatly, however, and in most cases is due to a real dispersion in star formation activity. This activity is only weakly correlated with galaxy luminosity or H I content, suggesting that some other parameter is more important.
- Publication:
-
The Astronomical Journal
- Pub Date:
- August 1983
- DOI:
- 10.1086/113399
- Bibcode:
- 1983AJ.....88.1094K
- Keywords:
-
- Astronomical Spectroscopy;
- Emission Spectra;
- H Alpha Line;
- Spiral Galaxies;
- Stellar Evolution;
- Virgo Galactic Cluster;
- B Stars;
- Cosmic Dust;
- H Ii Regions;
- Hubble Constant;
- Instrument Errors;
- Nitrogen;
- Nuclear Reactions;
- O Stars;
- Star Formation Rate;
- Astrophysics