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ASCA Observation of the polar RX J1802.1+1804

M. Ishida·J. Greiner·R. A. Remillard·C. Motch
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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 ~1keV and >7 keV, suggesting postshock cooling as observed in EX Hya. A remarkable feature of the spectrum is the strong iron K_alpha 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.

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M. Ishida, J. Greiner, R. A. Remillard, C. Motch. 1998-05-15. ASCA Observation of the polar RX J1802.1+1804. https://arxiv.org/abs/astro-ph/9805211

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