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Paper: Light Curves Analysis of Deeply Eclipsed Dwarf Nova GY Cnc
Volume: 509, 20th European Workshop on White Dwarfs (EuroWD16)
Page: 543
Authors: Voloshina, I.; Khruzina, T.
Abstract: The results of photometric observations of the dwarf nova GY Cnc in the Rc filter in 2013–2016 are presented, including observations during its outburst in April 2014. The orbital ephemerides of the system have been determined more accurately using these numerous data. The orbital period has not significantly changed during the ∼ 30000 orbital cycles since the earlier observations; no systematic variations of O–C were found out. The fluctuations within the limits 0.004d on a timescale of 1500–2000 Porb were detected. A combined model is used to solve for the parameters of GY Cnc for both states of the system. The donor star temperature, T2∼ 3667 K (Sp M0.2 V) varies between 3440 and 3900 K (Sp K8.8–M1.7 V). The semi-major axis of the disk is a0.22a0, on average. In quiet state, a varies within ∼ 40%. The disk has a considerable eccentricity (e0.2–0.3) for the small a values, a0.2a0. With increasing a the disk shape becomes more circular (e<0.1). The GY Cnc outburst is due to a sharp growth of the disk luminosity because of a diminution of αg parameter (which is related to the viscosity of the disk material) up to 0.1–0.2, and the temperature of the disk interiors increasing twofold to Tin∼ 95000 K. These changes were probably due to infall of matter onto the surface of white dwarf as the outburst developed. For all accretion disk parameters in a quiet state considerable variations about their mean values are typical.
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