Nature of the halos of spiral galaxies
Abstract
Some concrete limits are placed on the possible nature of the matter constituting the coronae of spiral galaxies, including our own. The hypothesis of Einasto et al. (1974) that such a coronae consists of hot ionized gas is shown to contradict observational data on the soft X-ray background, the soft X-ray flux from M31, and estimates of the UV flux from M31. The hypothesis that the corona may consist of stars (dwarfs or subdwarfs of spectral type M5 or later) is shown to infer that such 'coronal' stars should exist in the vicinity of the sun with a space density of about 0.01 per cu pc and a velocity dispersion of about 300 km/sec. It is noted that this inference can be avoided if the hypothesized coronal stars are concentrated in dwarf clusters or even in dwarf galaxies.
- Publication:
-
Soviet Astronomy Letters
- Pub Date:
- April 1975
- Bibcode:
- 1975SvAL....1...47K
- Keywords:
-
- Coronas;
- Galactic Structure;
- Spiral Galaxies;
- Star Clusters;
- Dwarf Stars;
- Subdwarf Stars;
- Ultraviolet Radiation;
- X Ray Astronomy;
- Astrophysics