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Paper: Observational Evidence for a Complex Magnetic Field Structure of the Asynchronous Polar BY Cam
Volume: 372, 15th European Workshop on White Dwarfs
Page: 537
Authors: Pavlenko, E.; Babina, Ju.; Andreev, M.
Abstract: We present the result of a photometric study of the asynchronous polar BY Cam in its low accretion state in 2004 - 2006. The mean brightness display a four-humped variation in phase with the 14.6 d beat period. The shape of the spin light curve depends on the magnetic field orientation in respect to the secondary component (i.e. on the beat phase). Three-humped light curves with separate humps displaced at 0.25 spin phase are observed at the opposite beat phases ~0.2 and ~0.7 and two-humped light curves at other phases. The O-C for the main hump shows jumps, systematical and chaotical behavior at definite beat phases. We suggest these peculiarities are caused by accretion in a complex magnetic field with a strong quadrupole component. The amplitudes of the humps, associated with dipole accretion poles, vary with the beat phase, pointing to unequal accretion onto the diametrically oriented poles, when each of them reaches the same azimuth, most favorable for accretion.
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