Search for Ionized Cores in Proto--Planetary Nebulae, and the Asymptotic Giant Branch to Planetary Nebula Transition
Abstract
Preliminary evaluations are made of the time taken by the circumstellar dust shells to become optically thin at visible and near-IR wavelengths, following the termination of the superwind envelope ejection. The typical thinning times are estimated at 1000 and 100 yr at H-alpha and Br-alpha wavelengths, respectively. Results of observations are then presented for a sample of candidate transition objects. The results imply transition times in excess of 1000 yrs for most post-AGB stars, and therefore the transition time may be comparable to the nebular age in a fair fraction of known planetary nebulae.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1993
- DOI:
- 10.1086/172741
- Bibcode:
- 1993ApJ...410..251K
- Keywords:
-
- Asymptotic Giant Branch Stars;
- Planetary Nebulae;
- Protoplanets;
- Stellar Cores;
- Stellar Evolution;
- Hydroxyl Emission;
- Interstellar Extinction;
- Stellar Envelopes;
- Stellar Spectrophotometry;
- Astrophysics;
- ISM: PLANETARY NEBULAE: GENERAL;
- STARS: CIRCUMSTELLAR MATTER;
- STARS: EVOLUTION;
- STARS: INTERIORS