Extreme ultraviolet observations of white dwarfs
Abstract
Observations shortward of the hydrogen Lyman limit provide sensitive determinations of stellar temperatures and interstellar absorption. Such data are of particular value in studies of hot white dwarfs, for which a large fraction of the emission occurs in the extreme-ultraviolet band (100-1000 A). Observations of HZ 43 and Feige 24 have been obtained with the Apollo-Soyuz extreme-ultraviolet telescope; both stars are copious EUV emitters, with four billionths and three billionths erg/sq cm sec in the 170-620-A band, respectively. The EUV data, combined with optical spectrophotometry, allow their temperatures to be estimated as 80,000 and 60,000 K, respectively. The corresponding interstellar neutral hydrogen column densities are about 4 by 10 to the 18th power per sq cm.
- Publication:
-
Highlights of Astronomy
- Pub Date:
- 1977
- DOI:
- 10.1017/S1539299600003543
- Bibcode:
- 1977HiA.....4B.341L
- Keywords:
-
- Apollo Soyuz Test Project;
- Far Ultraviolet Radiation;
- Radiant Flux Density;
- Ultraviolet Astronomy;
- White Dwarf Stars;
- Interstellar Extinction;
- Radiation Counters;
- Spectral Energy Distribution;
- Stellar Atmospheres;
- Stellar Temperature;
- X Ray Astronomy;
- Astrophysics