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Paper: On the nature of the new below-gap intermediate polar RX J1238-38
Volume: 157, Annapolis Workshop on Magnetic Cataclysmic Variables
Page: 51
Authors: Buckley, David; Cropper, Mark; Ramsay, Gavin; Wickramasinghe, Dayal; Hellier, Coel; Beardmore, Andrew
Abstract: The ROSAT source rxj is a new member of the intermediate polar class of magnetic cataclysmic variables. Optical photometry has revealed two coherent periodicities, at 1860 s and 2147 s, with similar amplitudes of ~8%. An initial hypothesis that these two periods were the spin and synodic (i.e. beat) periods, respectively, was not supported by subsequent spectroscopic observations. The emission lines vary only at the 2147-s period, and radial velocity variations are detected at this, and a longer period of ~5300 plus or minus 1000 s, which are interpreted as the spin and orbital periods, respectively. In addition, X-ray observations with ASCA and RXTE confirm the 2147-s spin period. The 1860-s period is thus most likely to be the first harmonic of the omega-Omega sideband. rx therefore joins EX Hya as an intermediate polar below the 2-3 hr period gap. It is somewhat further from synchronism than EX Hya, but not as asynchronous as the above-gap IPs. Furthermore, its orbital period is close to the minimum for CVs with non-degenerate secondaries.
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