ASCA X-ray observations of EX Hya: spin-resolved spectroscopy |
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| Authors: | AlasdairAllan CoelHellier rewBeardmore |
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| Institution: | Department of Physics, Keele University, Keele, Staffordshire ST5 5BG |
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| Abstract: | We analyse the spectral changes over the spin modulation in the intermediate polar EX Hya using archival ASCA data. We find that the modulation can be modelled as either (1) the effect of occultation of the accretion poles by the limb of the white dwarf, or (2) the effect of phase-dependent photoelectric absorption. We argue, on the basis of the partial X-ray eclipse, that the accretion columns in the system are tall, with shock height ～ R wd, and hence that the spin modulation is caused mainly by occultation. We find that the temperature distribution along the accretion shocks is incompatible with the calculations of Aizu, except for a restricted parameter regime with a high M wd. Hence the material in the shock must cool faster than predicted by theory. |
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| Keywords: | accretion accretion discs binaries: close binaries: eclipsing stars: individual: EX Hya novae cataclysmic variables X-rays: stars |
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