Astronomy Reports

We present results of the study of maser emission variability in the 1665 MHz OH line in the G43.8–0.1 star formation region based on observations (monitoring) in 2008–2022 at the Large Radio Telescope in Nancy (France). Variability of all polarization parameters of the majority of spectral features, which has a monotonic regular character, has been found. Spatial identification of the main spectral features of the OH 1665 MHz line with maser spots (condensations) on the VLA map has been carried out. For the Zeeman pair $${{V}_{{{\text{LSR}}}}} = 44.15$$ km/s, a monotonic change of the splitting with time during 2008–2022 was found and, consequently, a change of the magnitude of the longitudinal magnetic field. According to our calculations, at the end of 2012, the direction of the magnetic field changed to the opposite. Сorrelated with $${{{\text{H}}}_{\parallel }}$$ , there were changes in the angle $$\chi $$ and, as a consequence, changes in the direction of the vector of the transverse magnetic field $${{{\text{H}}}_{ \bot }}$$ . For the maser feature at 44.5 km/s, a change of $${{{\text{H}}}_{ \bot }}$$ by 180° was found. In 2016–2022, some reorientation of the global magnetic field ( $${{{\text{H}}}_{ \bot }}$$ ) in G43.8–0.1 occurred. The field became less chaotic: in the eastern part, the field in maser condensations is perpendicular to the arc, and in the western part, it is parallel to the arc. It is assumed that the global magnetic field in the entire U H II region of the G43.8–0.1 source has the same direction: along the axis (northeast)—(southwest).

We present a new normalization for the linear density-perturbation spectrum in a multi-parameter model of the Universe. Using the differential mass function for the nearly galaxy clusters obtained from optical data, we have constructed a functional relation between the dispersion of the density contrast σ 8 on the scale 8h −1 Mpc and the cosmological parameters Ω m , ΩΛ, h, n, f v for each of three theoretical approximations of the mass function: Press-Schechter, Sheth-Tormen and Jenkins. An extended class of models of the Universe with general spatial curvature include four parameters for the matter components: baryons (Ω b ), “cold” dark matter (Ω c ), “hot” dark matter (Ω v ), and the vacuum energy (ΩΛ). It is shown that the most accurate normalization of the power spectrum is achieved with the Sheth-Tormen approximation.

Results of a study of powerful H2O maser flares in the W51 region from observations (monitoring) in 2009–2022 with the 22-m radio telescope in the Pushchino Radio Astronomy Observatory are presented. Three powerful maser flares were detected at radial velocities of 69.7, 61.6, and 59.0 km/s with flux densities at peaks of 23.1, 29.4, and 66.1 kJy, respectively. The first and third of them are identified with the main source (W51 Main). A probable reason for their occurrence may be the superposition of two maser condensations with close radial velocities on the line of sight. A large number of flares with flux densities above 10 kJy were also detected, most of which were identified with W51 North. The mechanism for the appearance of the asymmetry of the line for the most powerful flare at a radial velocity of 59 km/s is discussed.

The disk masses of four low-surface-brightness (LSB) galaxies are estimated using the criterion of marginal gravitational stability. The constructed mass models are close to those for a maximum disk. The results show that the disks of LSB galaxies may be significantly more massive than is usually believed based on their brightnesses. In this case, their surface densities and masses are fairly typical for higher-surface-brightness spirals. Alternatively, it may be that LSB disks are dynamically overheated.

A catalog of Galactic globular clusters has been compiled and used to analyze relations between the chemical and kinematic parameters of the clusters. The catalog contains positions, distances, luminosities, metallicites, and horizontal-branch morphology indices for 157 globular clusters, as well as space velocities for 72 globular clusters. For 69 globular clusters, these data are suppleented with the relative abundances of 28 chemical elements produced in various nuclear-synthesis processes, taken from 101 papers published between 1986 and 2018. The tendency for redder horizontal branches in lowmetallicity accreted globular clusters is discussed. The discrepancy between the criteria for cluster membership in the thick-disk and halo subsystems based on chemical and kinematic properties is considered. This is manifest through the fact that all metal-rich ([Fe/H] > −1.0) clusters are located close to the center and plane of the Galaxy, regardless of their kinematic membership in particular Galaxy subsystems. An exception is three accreted clusters lost by a dwarf galaxy in Sagittarius. At the same time, the fraction of more distant clusters is high among metal-poorer clusters in any kinematically selected Galactic subsystem. In addition, all metal-rich clusters whose origins are related to the same protogalactic cloud are located in the [Fe/H]–[α/Fe] diagram considerably higher than the strip populated with field stars. All metal-poor clusters (most of them accreted) populate the entire width of the strip formed by high-velocity (i.e., presumably accreted) field stars. Stars of dwarf satellite galaxies (all of them being metal-poor) are located in this diagram much lower than accreted field stars. These facts suggest that all stellar objects in the accreted halo are remnants of galaxies with higher masses than those in the current environment of the Galaxy. Differences in the relative abundances of α-process elements among stellar objects of the Galaxy and surrounding dwarf satellite galaxies confirmthat the latter have left no appreciable stellar traces in the Galaxy, with the possible exception of the low-metallicity cluster Rup 106, which has low relative abundances of α-process elements.

From April 2021 to October 2022, in the monitoring data obtained daily at the Big Scanning Antenna radio telescope (BSA LPI), 11 events were identified for which X-ray flares in the solar corona were followed by magnetic storms on Earth. Interplanetary scintillation monitoring data were considered together with data on solar flare activity and a simple kinematic model of ejection propagation. Based on the estimated ejection velocity between the Sun and the probed region, under the assumption of a constant velocity, the time of arrival of the ejection to the Earth was calculated. Of the 11 events considered, 7 are associated with solitary flares followed by a coronal mass ejection (CME) and 4 are more complex and possibly associated with corotating perturbations or a superposition of corotating and flare perturbations. For the entire set of events, the average time of the real onset of a magnetic storm after the time predicted by the model was 3.6 h and the average time between the onset of scintillation enhancement and the onset of a magnetic storm was 20.1 h. For events associated with solitary flares, the magnetic storm began, on average, 0.8 hours after the predicted time and 15.6 hours after the onset of scintillation enhancement. The delay of magnetic storms with respect to the predicted time is apparently related to the deceleration of the ejection between the probed region of the solar wind and the Earth’s orbit.

The first results of a search for pulsars using the Large Phased Array of the Lebedev Physical Institute at 111 MHz for right ascensions 0h-24h and declinations 21°-42° are reported. Data with a time resolution of 100 ms in six frequency channels within a 2.5-MHz frequency band have been processed. Thirty-four pulsars have been detected, of which seventeen were observed on this telescope earlier; ten known pulsars had not been observed earlier. Seven new pulsars have been discovered.

A reconstruction of the total mass (the fraction of dark matter, intercluster gas, and the brightest galaxy of the cluster) of 128 X-ray galaxy clusters at redshifts 0.01–1.4 based on Chandra observations is presented. The total mass M 200 and the baryonic mass M b have been measured for all the sample objects, as well as the concentration parameter c 200, which characterizes the size of the dark matter halo. The existence of a tight correlation between c 200 and M 200 is confirmed, c ∝ M vir /(1 + z) b with a = −0.56 ± 0.15 and b = 0.80 ± 0.25 (95% confidence level), in good agreement with the predictions of numerical simulations and previous observations. Fitting the inner dark-matter density slope α with a generalized NFW model yields α = 1.10 ± 0.48 at the 2σ confidence level, combining the results for the entire sample, for which the model gives a good description of the data. There is also a tight correlation between the inner slope of the dark-matter density profile α and the baryonic mass contentM b for massive galaxy clusters, namely, α decreases with increasing baryonic mass content. A simple power-law model is used to fit the α − M b distributions, yielding the break point for the inner slope of the dark-matter density profile b = 1.72 ± 0.37 (68% confidence level).