The Evolution of the Central Stars of Planetary Nebulae.
Abstract
A new temperature scale for the planetary nebulae is derived based upon the H recombination line of ionized hydrogen of the nebular shell and the photographic magnitude of the central star. The temperatures are systematically larger than those derived by Berman. The mean sizes of the nebular shells are used to indicate the time scale of the changes occurring in the central stars. The stars are seen to be in a rapidly contracting state with the radius shrinking from over 1 solar radius to one-one hundredth of the solar radius in a time scale of 25000 years, while the effective temperature rises from 40000 to 150000 K, thereby entering regions of almost complete degeneracy. it is shown that these star + nebula systems represent the gravitational-collapse phase of evolution of stars of about 1.2 solar masses as their nuclear fuel-burning is completed The stars, having passed through the state having planetary nebulae, can account for a large fraction of the presently observed white dwarfs.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1963
- DOI:
- 10.1086/147618
- Bibcode:
- 1963ApJ...138...67O