Schwarz, R. and Schwope, A. D. and Staude, A. and Rau, A. and Hasinger, G. and Urrutia, T. and Motch, C. (2007) Paloma (RX J0524+42): the missing link in magnetic CV evolution? Astronomy and Astrophysics, 473 (2). pp. 511-521. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:SCHWaanda07
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Decent optical photometry of the candidate magnetic CV Paloma has uncovered three persistent periods at 157, 146, and 136 min, which we interpret as the manifestation of the orbital motion of the system, the white dwarf’s spin, and a related side-band frequency of the other two. All three periodicities are caused by a double-humped modulation of about 1 mag appearing only at certain fractions of the beat cycle, and it probably originates from one or two accretion spots. Our data is consistent with two plausible solutions, with the spin period being either 146 or 136 min. The appearance of a corresponding spin-folded light curve suggests two different scenarios, for which either pole switching between two diametrically opposed accretion regions (for Pspin = 146 min) or pole migration of one single spot (with Pspin = 136 min) is the preferred accretion mode. Complementary ROSAT X-ray observations and low-resolution spectroscopy provide supporting evidence of the magnetic nature of the object. Depending on the choice of the spin period, the degree of asynchronism with respect to the orbital period is 7% or 14%, implying a beat period of 0.7 or 1.4 days. Thus, the source populates the gap between the near-synchronous polars (<2%) and the DQ Herculis stars with long spin periods (e.g. EX Hya, V1025 Cen, DW Cnc). With an orbital period right within the period gap, Paloma is a key object for magnetic CV evolution: it might be the first bona fide transition object between the DQ Her and AM Her system with a white dwarf currently in the process of synchronisation.
|Additional Information:||© ESO 2007 Received 20 April 2007 / Accepted 14 June 2007 R.S. and A.S. are supported by the Deutsches Zentrum für Luft- und Raumfahrt (DLR) GmbH under contract No. FKZ 50 OR 0404. A.S. gratefully acknowledges funding by the Deutsche Forschungsgemeinschaft under contract SCHW536/20-1.|
|Subject Keywords:||accretion, accretion disks – magnetic fields – X-rays: binaries – stars: novae, cataclysmic variables – stars: individual: RX J0524+42|
|Official Citation:||Schwarz, R., Schwope, A. D., Staude, A., Rau, A., Hasinger, G., Urrutia, T., and Motch, C. (2007) Paloma (RX J0524+42): the missing link in magnetic CV evolution? Astronomy & Astrophysics, 473(2):511-521, October 2007. http://dx.doi.org/10.1051/0004-6361:20077684|
|Usage Policy:||You are granted permission for individual, educational, research and non-commercial reproduction, display and performance of this work in any format.|
|Deposited By:||Arun Sannuti|
|Deposited On:||11 Dec 2007|
|Last Modified:||26 Dec 2012 09:47|
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