Vol 45, No 4 (2019)

We analyze new observational data obtained at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the SCORPIO focal reducer for the peculiar galaxy UGC 1198. Based on these data, we have concluded that UGC 1198 is a dwarf elliptical galaxy (dE) with evidence of interaction. A kinematic study of UGC 1198 has shown that at least two systems are observed in this object. One of them is associated with the stellar system of UGC 1198 itself with weak rotation around the minor axis of the galaxy. The second system is associated with the gaseous disk/ring rotating at an angle of 72° to the equatorial plane of the galaxy. The gaseous polar disk/ring could be formed during the merger of a dwarf elliptical galaxy with a galaxy of approximately the same or lower mass containing a gas. The mean age of the stellar population at r ≥ 5″ is 2 × 10⁹ yr. The interaction as a result of which the galaxy under study was formed can be assumed to have occurred less than one billion years ago.

We consider open star clusters (OSCs) with the proper motions, parallaxes, and line-of-sight velocities calculated by various authors from Gaia DR2 data. The distance scale factor has been found by analyzing the separate solutions of the basic kinematic equations to be p =1.00 ± 0.04. It shows that the distances calculated using the parallaxes from the Gaia DR2 catalogue do not need any correction factor. We have investigated the solutions obtained from various OSC samples differing in both age and accuracy of their parallax and line-of-sight velocity measurements. The solution obtained from a sample of 930 OSCs satisfying the constraints on the age log t < 9.0 and the relative trigonometric parallax error <30% is recognized to be the best one, with 384 OSCs in this sample having the mean line-of-sight velocities calculated from at least three probable members of the corresponding clusters. As a result of the simultaneous solution of all the basic kinematic equations, we have found the following kinematic parameters from this sample: (U, V, W)_⊙ = (8.53, 11.22, 7.83) ± (0.38, 0.46, 0.32) km s⁻¹, Ω₀ = 28.71 ± 0.22 km s⁻¹ kpc⁻¹, Ω′₀ = −4.100 ± 0.058 km s⁻¹ kpc⁻², and Ω″₀ 0.736 ± 0.033 km s⁻¹ kpc⁻³. The linear rotation velocity at the adopted at the adopted solar distance R₀ = 8.0 ± 0.15 kpc is V₀ = 229.7 ± 4.6 km s⁻¹. An analysis of the proper motions for these 930 OSCs has shown that, apart from the rotation around the Galactic z axis, there is rotation of the entire sample around the x axis with an angular velocity of 0.48 ± 0.15 km s⁻¹ kpc⁻¹ differing significantly from zero.

For the classical Cepheid V1033 Cyg we have constructed an O—C diagram spanning a time interval of 117 years. The O—C diagram has the shape of a parabola, which has made it possible to determine for the first time the quadratic light elements and to calculate the rate of evolutionary increase in the period dP/dt = 18.19 (±0.08) syr⁻¹, in agreement with the results of theoretical calculations for the first crossing of the instability strip. Thus, V1033 Cyg is the second actually observed Cepheid (after α UMi) that crosses the instability strip for the first time.

The energy distribution of weak emission events (nanoflares) in the solar corona measured for two stages of solar cycle 24, at the minimum and at the beginning of the rise in solar activity, is presented. Our study is based on data from two instruments, TESIS/CORONAS-PHOTON (for the cycle minimum; 2009) and AIA/SDO (the rising phase, 2010–2011), for which we have applied a unified event detection algorithm. The database collected by us comprises more than 10⁵ flares. For all events we have measured the flux in the EUV spectral range and determined the thermal energy located in the range from 10²³ to 10²⁶ erg and distributed according to a power law: N(E)dE ∼ N^−αdE. The index of the power-law distribution α in all of the cases studied has turned out to be more than two (α = 2.2–2.9). This means that the integrated energy of nanoflares increases when passing to weaker events. This scenario argues for the model of coronal heating by nanoflares. The index α reaches its maximum at the cycle minimum and then drops, implying a decrease in the fraction of weak events. This may be because part of the energy is redistributed in favor of large flares. The total energy of nanoflares in the range 10²³–10²⁶ erg has turned out to be lower than the energy losses of the solar corona through radiation by a factor of 30. For the coronal heating to be explained by nanoflares, their distribution with the same power-law index must extend at least to 10²¹ erg.