Soft X-ray characteristics of white dwarfs observed by EXOSAT
Abstract
EXOSAT has observed 19 hot white dwarfs with alleged strong soft X-ray emission. Positive detection of a large fraction of this sample was obtained, among these practically all hot DA dwarfs. High-resolution spectral data, acquired with the 500 1/mm grating spectrometer, indicates no traces of He in the atmosphere of HZ43, i.e. n(He)/n(H) <= 10-5 at a photospheric temperature of 60000 K (log g = 8). In contrast, the hot DA1 dwarf Feige 24 shows the presence of an appreciable He-abundance (n(He)/n(H) >= 10-3) however no simple homogeneously mixed H/He atmosphere can explain the observed spectral shape.
- Publication:
-
Advances in Space Research
- Pub Date:
- 1985
- DOI:
- 10.1016/0273-1177(85)90451-X
- Bibcode:
- 1985AdSpR...5c..61H
- Keywords:
-
- Exosat Satellite;
- Stellar Spectra;
- White Dwarf Stars;
- X Ray Astronomy;
- High Resolution;
- Hot Stars;
- Spectrum Analysis;
- Stellar Temperature;
- X Ray Spectra;
- Astrophysics