Vol 32, No 4 (2016)

The dark energy model with barotropic equation of state, which interacts with dark matter by gravitation and by other force, which causes the energy-momentum exchange between them, is considered. Both components are described in approximation of ideal fluid, which are parameterized by density, equation of state and effective sound speed parameters. The three types of interactions between dark components are considered: interaction independent from their densities, interaction proportional to energy density of dark energy, and interaction proportional to energy density of dark matter. The equations that describe the expansion dynamics of homogeneous and isotropic Universe and evolution of densities of both components for different values of interaction parameter are obtained on the bases of the general covariant conservation equations and Einstein’s ones. For three kinds of interactions, the existing of the range of values of parameters of dark energy for which the densities of dark components are negative was shown. The conditions of positivity of energy density of dark energy and dark matter were written for which the constraints on the value of parameter of interaction were derived. The dynamics of expansion of the Universe with these interactions of dark energy and dark matter is analyzed.

Results of 11-year-long X-ray INTEGRAL observations of the nucleus of Seyfert galaxy NGC 4945 in the 3–500 keV range were processed. A two-component spectrum model, which includes strong radiation absorption in the Compton-thick torus around the AGN “central engine” and secondary radiation reflected from the torus walls, was used in the analysis. The following primary spectrum parameters were determined based on the data accumulated throughout the entire exposure period: photon index Γ = 1.60 ± 0.07, exponential cutoff energy E_c =157_-22⁺²⁹ keV, and column density of the medium that absorbs primary radiation N_H,1 =5.0_-0.9^+1.0 × 10²⁴ cm^–2. The column density of the medium absorbing reflected radiation is two orders of magnitude lower. Both the X-ray flux in the ranges of 20–40, 40–60, and 60–100 keV and the shape of the X-ray spectrum of NGC 4945 vary. The spectrum shape variations may be induced by inhomogeneities of the absorbing medium surrounding the AGN. At the same time, there is some evidence for moderate spectrum variations in the highenergy region, which may be associated with changes in the “central engine.”

Pressure dependences of the volume scattering coefficient of aerosol in the atmosphere of Jupiter σ_a(P) are presented. In calculations carried out with separating the gaseous and aerosol absorption, the absorption of light in the continuous spectrum was taken into account. In the analysis, the spectrophotometric data of Jupiter for the absorption bands of methane at 727 and 619 nm—the geometric albedo (measured in 1993) and the reflectivity of some latitudinal details (measured in 2013)—were used. At high tropospheric levels, in the pressure range from 0.4 to 2 bar, the dependences σ_a(P) for the integral disk and latitude belts of the giant planet turned out to be similar. In this part of the atmosphere, the three thickest cloud layers were found; in these layers, within the pressure range from 0.8 to 1.33 bar in the North and South Temperature Belts (NTB and STB), respectively, the values of the coefficient σ_a(P) are maximum. In the pressure interval from 2 to 4 bar, in the analyzed latitude belts except the NTB and STB, the forth aerosol layer was found; its altitude position and vertical structure substantially differ from belt to belt. One more aerosol layer probably exists deeper in the atmosphere; its initial level and extension differ in different latitude belts. Most of the investigated latitude belts exhibit the spectral dependence of σ_a(P) at the atmospheric levels, where the pressure exceeds 3 bar. This probably points to the change in size or nature of aerosol particles.

Ionospheric disturbances at an altitude of 300 km that accompanied the solar eclipse of March 20, 2015, have been analyzed based on the ionosondes located in Europe. It has been confirmed that the eclipse was accompanied by the generation of gravity waves in the neutral atmosphere and traveling ionospheric disturbances. The period of the latter was 30–100 min, and the amplitude of relative electron density disturbances was 4–19%. The disturbances continued for not less than 2 h. During the eclipse, the disturbance amplitude more frequently increased. It decreased in one case, since the wave process observed previously was suppressed by the process generated by the eclipse.

The catalogue of positions and stellar V magnitudes of up to 17^m stars in the declination zone from 2° to 5.5° has been compiled. The catalogue includes 2.05 × 10⁶ stars and is based on the observations performed in 2010–2015 on the meridian axial circle (MAC) of GAO NAN Ukraine and the Astronomical Observatory of Taras Shevchenko National University. The errors of the positions and photometry for stars of 11–14 magnitude are 0.06″–0.08″ and 0.04^m–0.08^m, respectively.