Том 60, № 11 (2016)

The possible application of a Rindler type reference frame for studies of physical processes near the horizons of black and white holes is considered. New similar reference frames inside black and white holes in the region T of a Kruskal wormhole are introduced.

The results of photometric observations of the dwarf nova GY Cnc in the Rc filter acquired in 2013–2015 (~3900 orbital cycles, 19 nights in total) are presented, including observations during its outburst in April 2014. The binary’s orbital elements have been refined. The orbital period has changed only insignificantly during the ~30 000P_orb since the earlier observations; no systematic O–C variations were detected, only fluctuations within 0.004^d on time scales of 1500–2000P_orb. A “combined” model is used to solve for the parameters of GY Cnc during two states of the system. The flux from the white dwarf is negligible due to the star’s small size. The temperature of the donor star, 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 a ~ 0.22a₀, on average. In quiescence, a varies within ~40%. The disk has a considerable eccentricity (e ~ 0.2−0.3) for a < 0.2a₀. The disk shape becomes more circular (e < 0.1) with increasing a. The outburst of GY Cnc was associated with increased luminosity of the disk due to the parameter α_g (related to the viscosity of the disk material) decreasing to 0.1–0.2 and the temperature in the inner parts of the disk increasing twofold, to T_in ~ 95 000 K. These changes were apparently due to the infall of matter onto the surface of the white dwarf as the outburst developed. All parameters of the accretion disk in quiescence display considerable variations about their mean values.

The photometric variability of the M dwarf KIC 1572802 has been studied using the most complete observational data, obtained by the Kepler Space Telescope. Power spectra constructed from 59 488 single brightness measurements over 1460 days (~4 yr) show complex brightness variations. It is suggested that two peaks corresponding to the periods P = 0.37088^d and P = 0.37100^d are related to the presence of active regions at different latitudes on the differentially rotating star. Maps of the surface temperature inhomogeneities are used to derive the positions of these active regions. Analysis of these maps suggests that a switch in the active latitudes occurred 590 days after the beginning of the observations. The variations of the positions of the active regions are also analyzed. These high-temporal-resolution observations revealed a short time-scale change in the active latitudes lasting about 7^d, followed by a “flip-flop,” for the first time. The fraction of the surface of KIC 1572802 covered by spots is S ~ 7%. Comparison with literature data indicate that this S value for KIC 1572802 is substantially higher than the average spottedness of stars with temperatures of 3500–4500 K. This may indicate enhanced activity of KIC 1572802. The parameters of the differential rotation of the star are estimated; the inferred rotational velocity, Ω = 0.0056 ± 0.0010, is substantially lower than the solar value, but comparable to Ω for the cool dwarfs HK Aqr and EY Dra. The value of the Rossby number Ro = 0.011 suggests that KIC 1572802 is in the saturation region of the diagram of Ro vs. X-ray luminosity. If the Ro value for KIC 1572802 is this low, this implies that its magnetic field is of the order of tens or even hundreds of Gauss.