Spectroscopy of the central stars of three evolved planetary nebulae
Abstract
We present results of a spectroscopic project that aims at investigations of stars in the upper left part of the HRD. We observed the central stars of the three old planetary nebulae PN G011.4+17.9, PN G308.2+07.7, and PN G332.5-16.9. The spectra (echelle) were analysed by fitting the H and Heii lines with theoretical profiles from a grid of non-LTE model atmospheres. The models are composed of H and He and disregard metal opacities. The three nuclei appear to be very hot (T_eff near 10(5) K) and comparison with post-AGB evolutionary tracks reveals that the masses range between 0.55 and 0.75 M_⊙; the central star of PN G332.5-16.9 shows an enrichment in He and probably also in C and N. Based on observations collected at the European Southern Observatory, La Silla, Chile
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 1997
- Bibcode:
- 1997A&A...328..598S
- Keywords:
-
- WHITE DWARFS;
- PLANETARY NEBULAE: INDIVIDUAL: PN G011.4+17.9;
- PN G308.2+07.7;
- PN G332.5-16.9;
- STARS ABUNDANCES;
- STARS: FUNDAMENTAL PARAMETERS