Ultraviolet Stars and the Interstellar Gas
Abstract
If luminous red giants evolve to white dwarfs via a very hot stage (ultraviolet star), then these stars may have a significant influence on the interstellar medium. We extend the analysis of Hills by considering the evolution of ultraviolet stars and how these stars affect the dynamics of the resulting H ii regions. Compared to 0 stars, the ultraviolet stars are more uniformly distributed and in regions of lower density so that the initial spheres are larger. H ii regions due to ultraviolet stars are very short-lived and hence unimportant in regions with hydrogen density n0 > 1 cm 2; but if most ultraviolet stars occur in a rather uniform intercloud medium with n0 0.1 cm-2, then their H ii regions fill about one-third of this space, produce a mean electron density about 0.03 cm -2, comparable to that indicated by pulsar dispersions, and cause acceleration of interstellar gas adequate to explain the observed interstellar motions. Subject headings: early-type stars interstellar matter - nebulae - ultraviolet
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1973
- DOI:
- 10.1086/152034
- Bibcode:
- 1973ApJ...181..115R