The X-ray stream-eclipsing polar RX J1802.1+1804
Abstract
We present X-ray and optical data of the newly discovered AM Her variable RX J1802.1+1804. This X-ray source was observed in the ROSAT All-Sky-Survey in September 1990 and subsequently discovered as a highly variable and soft X-ray source. Follow-up pointed observations confirmed the strong variability and revealed a periodic flux modulation including a sharp and nearly complete eclipse of the X-ray emission. Based on the shape and duration of this eclipse as well as the lack of optical eclipses we favour an interpretation in terms of a self-eclipse by the accretion stream. The X-ray spectrum averaged over the full period is dominated by soft emission below 0.5 keV. The ratio of soft (blackbody) to hard (bremsstrahlung) bolometric energy flux is 1670, distinguishing this object as another example of a polar with an extreme strong excess in soft X-rays.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1998
- DOI:
- 10.48550/arXiv.astro-ph/9803344
- arXiv:
- arXiv:astro-ph/9803344
- Bibcode:
- 1998A&A...336..191G
- Keywords:
-
- CATACLYSMIC VARIABLES;
- ACCRETION;
- STARS: MAGNETIC FIELDS;
- STARS: INDIVIDUAL: RX J1802.1+1804 = V884 HER;
- Astrophysics
- E-Print:
- 9 pages (LATEX) + 10 ps-figures), l-aa style, accepted for publ. in Astron. Astrophys.