Том 72, № 1 (2017)

We examine the star formation properties of galaxies with very thin disks selected from the Revised FlatGalaxy Catalog (RFGC). The sample contains 333 ultra-flat galaxies (UFG) at high Galactic latitudes, |b| > 10◦, with a blue major angular diameter of a ≥ 1.'2, blue and red apparent axial ratios of (a/b)_b > 10, (a/b)_r > 8.5 and radial velocities within 10 000 kms⁻¹. As a control sample for them we use a population of 722 more thick RFGC galaxies with (a/b)_b > 7, situated in the same volume. The UFG distribution over the sky indicates them as a population of quite isolated galaxies.We found that the specific star formation rate, sSFR_FUV, determined via the FUV GALEX flux, increases steadily from the early type to late type disks for both the UFG and RFGC–UFG samples, showing no significant mutual difference within each morphological type T. The population of UFG disks has the average HI-mass-to-stellarmass ratio by (0.25 ± 0.03) dex higher than that of RFGC–UFG galaxies. Being compared with arbitrary orientated disks of the same type, the ultra-flat edge-on galaxies reveal that their total HI mass is hidden by self-absorption on the average by approximately 0.20 dex.We demonstrate that using the robust stellar mass estimate via 〈B−K〉-color and galaxy type T for the thin disks, together with a nowaday accounting for internal extinction, yields their sSFR quantities definitely lying below the limit of −9.4 dex (yr⁻¹). The collected observational data on UFG disks imply that their average star formation rate in the past has been approximately three times the current SFR. The UFG galaxies have also sufficient amount of gas to support their observed SFR over the following nearly 9 Gyrs.

A complete astrophysical and dynamical study of the close visual binary system (CVBS) Finsen 350 (A7V + F0V), is presented. Beginning with the entire observational spectral energy distribution (SED) and the magnitude difference between the subcomponents, Al-Wardat’s complex method for analyzing CVBS was applied as a reverse method of building the individual and entire synthetic SEDs of the system. This was combined with Docobo’s analytic method to calculate the new orbits. Although possible short (approximately 9 years) and long period (of about 18 years) orbits could be considered taking into account the similar results of the stellar masses obtained for each of them (3.07 and 3.41 M_⊙, respectively), we confirmed that the short solution is correct. In addition, other physical, geometrical and dynamical parameters of this system such as the effective temperatures, surface gravity accelerations, absolute magnitudes, radii, the dynamical parallax, etc., are reported. The Main Sequence phase of both components with age around 0.79 Gyr is approved.

We report the results of photometric observations of a number of magnetic white dwarfs in order to search for photometric variability in these stars. These V-band observations revealed significant variability in the classical highly magnetized white dwarf GRW+70◦8247 with a likely period from several days to several dozen days and a half-amplitude of about 0_.^m 04. Our observations also revealed the variability of the well-known white dwarf GD229. The half amplitude of its photometric variability is equal to about 0_.^m 005, and the likely period of this degenerate star lies in the 10–20 day interval. This variability is most likely due to the rotation of the stars considered.We also discuss the peculiarities of the photometric variability in a number of other white dwarfs. We present the updated “magnetic field–rotation period” diagram for the white dwarfs.

The event of March 11, 2011 was used to study decimeter-wave microflares (MF) in solar active regions. A theoretical interpretation has been proposed for the nature and generation mechanism of decimeter-waveMFs, which is based on an analysis of the phenomenon of double plasma resonance and subsequent transformation of upper hybrid waves when they interact with low-frequency plasma waves. It is shown that MFs should form in the active regions between magnetic fields of opposite direction, where magnetic-field strength reaches 100–150 G in the transition region. We report the spectral properties of MFs computed with the allowance for inverse bremsstrahlung and cyclotron absorption and for the increment of upper-hybrid waves. It is shown that the transition region is the most likely place of MF generation within the framework of the model of electron-density and temperature. It is also shown that within the framework of electron density and temperature model in the active region the most likely MF generation place in the solar atmosphere is the transition region. MFs were observed at frequencies from 1.036 to 1.306 Hz, which is consistent with model computations.

The K2’s Campaign 9 (K2C9) by the Kepler satellite for microlensing observations towards the Galactic bulge started on April 7, 2016, and is going to last for about three months. It offers the first chance to measure the masses of members of the large population of the isolated dark low-mass objects further away in our Galaxy, free-floating planets (FFPs). Intentionally, this observational period of K2 will overlap with that of the 2016 Spitzer follow-up microlensing project expected to start in June, 2016. Therefore, for the first time it is going to be possible to observe simultaneously the same microlensing events from a ground-based telescope and two satellites. This will help in removing the two-fold degeneracy of the impact parameter and in estimating the FFP mass, provided that the angular Einstein ring radius Θ_E is measured. In this paper we calculate the probability that a microlensing event is detectable by two or more telescopes and study how it depends on the mass function index of FFPs and the position of the observers on the orbit.