On the number of planetary nebulae in our Galaxy.
Abstract
From several methods it has been estimated that the total number of planetary nebulae in our Galaxy lies in the 4000 to 22,000 range. This result is compared with those derived from other galaxies. It is found that the number of planetary nebulae per unit mass in the nucleus of M3 1 and in the halo of our Galaxy are smaller than that found in the solar vicinity. This last result implies that halo objects seldom become planetary nebulae. It is found that the contribution to the ionization of the interstellar medium due to planetary nebulae is from one to two orders of magnitude smaller than that due to 0 stars. The mass return to the interstellar medium due to planetary nebulae is investigated, and the birth rate of white dwarfs and planetary nebulae are compared. Several arguments are given against the possibility that the infrared sources detected by Becklin and Neugebauer in the direction of the galactic center are planetary nebulae. Subject headings: galaxies: nuclei interstellar: matter - nebulae: planetary - stars: stellar statistics
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1976
- DOI:
- 10.1086/154251
- Bibcode:
- 1976ApJ...205...74A