ASCA observation of the polar RX J1802.1+1804
Abstract
We present X-ray data of {RX J1802.1+1804} obtained by {ASCA}. Although it shows a clear orbital intensity modulation with an amplitude of nearly 100% below 0.5 keV in {ROSAT} data, the {ASCA} light curves are nearly flat except for a possible dip lasting about one-tenth of the orbital period. We discuss this within the model assumption of a stream-eclipsing geometry as derived from the ROSAT observations. The {ASCA} X-ray spectrum can be represented by a two temperature optically thin thermal plasma emission model with temperatures of ~ 1 keV and >7 keV, suggesting postshock cooling as observed in {EX Hya}. A remarkable feature of the spectrum is the strong iron {Kalpha } emission line whose equivalent width is ~ 4 keV. To account for this, an iron abundance of greater than at least 1.3 times Solar is required. A combined spectral analysis of the {ROSAT} PSPC and {ASCA} data indicates that the N_H-corrected flux ratio of the soft blackbody (0.1-2.4 keV) to the hard optically thin thermal plasma emission (2-10 keV) is as large as ~ 10(4) .
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1998
- DOI:
- 10.48550/arXiv.astro-ph/9805211
- arXiv:
- arXiv:astro-ph/9805211
- Bibcode:
- 1998A&A...336..200I
- Keywords:
-
- STARS: NOVAE;
- CATACLYSMIC VARIABLES;
- ACCRETION;
- ACCRETION DISKS;
- X-RAYS: STARS;
- STARS: INDIVIDUAL: RX J1802.1+1804 = V884 HER;
- Astrophysics
- E-Print:
- 9 pages (LATEX) + 9 ps-figures), l-aa style, accepted for publ. in Astron. Astrophys. 335