Discovery of an EUV-bright polar in the period gap from the ROSAT Wide Field Camera sky survey.
Abstract
The discovery of a new polar found during the all-sky survey of extreme-UV sources conducted by the UK Wide Field Camera on board ROSAT is reported. The V of about 16 object is the brightest EUV polar observed by this instrument during the survey. These and subsequent optical observations show that the orbital period of the system is 2.33 h, placing it well inside the cataclysmic variable 'period gap'. Results from preliminary optical photometry, spectroscopy, and polarimetry are presented and compared to other known polars. The ROSAT results indicate that the system exhibits a soft X-ray excess by at least a factor of about 2 over the hard bremsstrahlung component. The likely evolutionary status of this 'period gap' polar is discussed, and it is concluded that it was probably born in the gap rather than evolving through it from a longer period. The probable accretion geometry of the system is also discussed.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 1993
- DOI:
- 10.1093/mnras/262.1.93
- Bibcode:
- 1993MNRAS.262...93B
- Keywords:
-
- Cataclysmic Variables;
- Extreme Ultraviolet Radiation;
- Light Curve;
- Sky Surveys (Astronomy);
- Stellar Magnetic Fields;
- Stellar Mass Accretion;
- Accretion Disks;
- Emission Spectra;
- Rosat Mission;
- Stellar Radiation;
- X Ray Stars;
- Astronomy