The unique magnetic cataclysmic variable V1432 Aql

Third type of minima and synchronization

¹ Department of Astronomy, Odessa National University, T.G.Shevchenko Park, 65014 Odessa, Ukraine e-mail: il-a@mail.ru
² Crimean Astrophysical Observatory, 98409 Nauchny, Ukraine
³ Max-Planck-Institut für extraterrestrische Physik, 85741 Garching, Germany
⁴ Observatori Astronòmic de Mallorca, 07144 Costitx, Spain

Received: 29 August 2005
Accepted: 31 January 2006

Abstract

Results of a CCD study of the variability of the unique magnetic cataclysmic variable V1432 Aql from the Astronomical Observatory of Mallorca are presented. The “multi-comparison star” method had been applied for better accuracy estimates. The linear ephemeris based on 76 timings of orbital eclipses for 1993–2004 is For the wide minima due to the spin variability, the quadratic ephemeris   was determined. The rate of the spin-up of the white dwarf corresponds to the synchronization time-scale determined to be (96.7 ± 1.5) years, in an agreement with theoretical model of the accretion torque. A third type of minima was detected that occur with the spin period. It was interpreted as indicating presence of the second accretion column. For adopted values of mass and the estimated accretion rate is ~7  . Further multi-colour monitoring is needed to study of late stages of the “spin-orbital” synchronization and periodic changes of the accretion geometry caused by “idling” of the white dwarf.