ASCA observation of the polar RX J1802.1+1804
M. Ishida 1,
J. Greiner 2,
R.A. Remillard 3 and
C. Motch 4
Received 22 December 1997 / Accepted 14 April 1998
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 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 -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 .
Key words: stars: novae, cataclysmic variables accretion, accretion disks X-rays: stars stars: individual: RX J1802.1+1804 = V884 Her
Present address: Astrophysical Institute Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany (firstname.lastname@example.org)
Send offprint requests to: M. Ishida
© European Southern Observatory (ESO) 1998
Online publication: July 7, 1998