The effective temperatures of the O stars.
Abstract
Far-ultraviolet photometric observations (in 5 bands between 1550 A and 3300 A) are presented for ten O stars which are also the exciting stars of diffuse nebulae. Since the number of photons shortwards of the Lyman limit is known for these stars, sufficient information on the total flux is available to determine the effective temperature without making any assumptions concerning a model atmosphere. Conversely, the distribution of flux with wavelength can be used to determine the applicability of a given model. A detailed discussion of this is presented. It is concluded that existing models with log g = 4 or 4.5 fail to reproduce the observations, while the few models with log g = 3.5 are in better agreement. A comparison of these 'normal' O stars and stars with O-type spectra that excite planetary nebulae is given. It is concluded that the atmospheres of these two types of O star are very similar; they probably have the same effective gravity. A discussion of the Zanstra He II temperature is also presented.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1979
- Bibcode:
- 1979A&A....77..189P
- Keywords:
-
- O Stars;
- Radiant Flux Density;
- Stellar Spectrophotometry;
- Stellar Temperature;
- Ultraviolet Photometry;
- Astronomical Netherlands Satellite;
- Balmer Series;
- Bolometers;
- Excitation;
- Interstellar Extinction;
- Lyman Alpha Radiation;
- Photons;
- Planetary Nebulae;
- Stellar Atmospheres;
- Stellar Gravitation;
- Astrophysics;
- Atmospheres:O Stars;
- Effective Temperatures:O Stars;
- O Stars:Planetary Nebulae;
- O Stars:UV Photometry;
- O Stars:UV Spectra