Search for EUV emission from hot subdwarfs in the ROSAT wide-field camera survey.
Abstract
A search for positional coincidences of catalogued hot subdwarfs with sources detected in the ROSAT wide-field camera (WFC) EUV survey is conducted. Six such coincidences are found. Optical follow-up observations reveal four of these stars to be hot DA white dwarfs (plus one other, less certain DA), previously misclassified as subdwarfs. These five are all within the 90 percent confidence levels of the WFC source positions, and are therefore reliable identifications with a class of sources known to be detectable EUV emitters. The remaining star is confirmed to be a hot, helium-rich subdwarf. This star lies just outside the 90 percent confidence level of the weak WFC source position. The possibility that this could be the first detection of EUV emission from a hot subdwarf is discussed. Upper limits are derived for several well-known, brighter hot subdwarfs which were not detected in the WFC survey.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 1992
- DOI:
- 10.1093/mnras/256.1.1
- Bibcode:
- 1992MNRAS.256....1S
- Keywords:
-
- Extreme Ultraviolet Radiation;
- Hot Stars;
- Rosat Mission;
- Spaceborne Astronomy;
- Subdwarf Stars;
- Ultraviolet Emission;
- Sky Surveys (Astronomy);
- Stellar Spectra;
- White Dwarf Stars;
- Wide Angle Lenses;
- Astronomy