Catalogue and luminosity function of white dwarfs detected in the ROSAT all-sky survey.
Abstract
This paper contains a compilation of all white dwarf stars known to have been detected at soft X-ray wavelengths by the Position Sensitive Proportional Counter onboard ROSAT during the all-sky survey phase of the mission. Out of the ~55,000 X-ray sources which have been detected in the ROSAT all-sky survey, only 175 are white dwarfs. Most (161) are of type DA, while there are 8 PG 1159, 3 DAO, and 3 DO stars detected. These numbers are compared to the results of the ROSAT Wide Field Camera survey and the log N - log S relation is used to estimate the completeness of the catalogue. The sky coverage of the ROSAT all-sky survey is used to calculate the X-ray luminosity function of DA white dwarfs. We find that only 10% of hot (i.e. T_eff_>20,000K) DAs are X-ray luminous (i.e. L_X_>10^29^ergs/s). We also use this sample to infer that one out of every four DAs are in binary systems with a late-type companion. This work represents the first all-sky X-ray survey of white dwarfs to a uniform sensitivity limit.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 1996
- Bibcode:
- 1996A&A...316..147F
- Keywords:
-
- STARS: WHITE DWARFS;
- STARS: STATISTICS;
- X-RAYS: STARS;
- SURVEYS