In this paper, for each visual component of 65 visual binary and multiple stars of the Pulkovo research program, the parallaxes and radial velocities from the Gaia DR3 catalogs (if available) are presented. Uncertainties of these parameters, as well as the RUWE parameter, are analyzed. It has been shown that, if the data for visual components with internal subsystems are excluded from the data under consideration, the typical uncertainties of the Gaia DR3 parallaxes and radial velocities are 0.020 mas (85 components) and 0.14 km/s (60 components), respectively. The other possible causes of large errors of the analyzed data are discussed. We compare the radial velocities from the Gaia DR3, NSS, and ground-based observational data for five systems of stars. The mass estimates for 34 components of 22 systems under consideration are also compared. We found a possible systematic difference between the Gaia DR3 and MSC masses data. This difference amount to –0.06 solar masses for 31 of the 34 components. The paper is partly based on the talk presented at the Modern Stellar Astronomy 2025 conference.
The results of the study of the star-forming region W75 N in the H2O 1.35 cm and OH 18 cm lines during 2021–2025 are presented. Observations in H2O were carried out with the RT-22 telescope in Pushchino, and in the OH lines with the Large Radio Telescope in Nançay (France). Strong, closely timed flares of maser emission were detected in spectral features of H2O in the 22 GHz line and OH in the 1665 and 1720 MHz lines at radial velocities of 10.3, 3.5, and 8.5 km/s, respectively. Fainter and shorter-lasting flares were observed in the OH 1667 MHz line. Flare activity for the principal features in all lines began in 2021. Strong flares in the 22 GHz, 1665 MHz, and 1720 MHz lines are associated with maser spots located in the VLA 1 radio jet. Their occurrence may be related to the passage of MHD waves that excite maser emission in the corresponding layer of the envelope fragment. Flares in the OH 1667 MHz line at radial velocities of 0.22, 0.40, and 4.4 km/s, whose maxima were observed in 2021 and 2024, are associated with the Keplerian disk of VLA 2.
Recent observations at the ALMA ground-based observatory and the James Webb Space Telescope suggest that galaxies are formed at redshifts of z 20. This paper notices that the observed profiles of the velocity dispersion of dark matter (DM) halos in low-mass galaxies of the Local Group are well described by a profile appearing in numerical models of DM halos, and the estimate of entropy of these galaxies is consistent with the theoretical estimates of background entropy of baryons at z 20. It has been shown that the structure of the first dwarf galaxies may be close to the Lane–Emden model, and their minimum mass, Mmin 107 M_⊙ , is determined by the background entropy of baryons formed after recombination due to Compton scattering of the cosmic microwave background radiation on electrons of weakly ionized plasma.
We present the results of monitoring the magnetar RX J2143.0+0654, which is a member of the Magnificent Seven, in a period of 2012 to 2024. The monitoring was carried out on the Big Scanning Array (BSA) radio telescope of the Lebedev Physical Institute of the Russian Academy of Sciences at a frequency of 111 MHz in a receiving band of 2.5 MHz. The radio emission from the magnetar was detected, and the dispersion measure DM = 11 ± 1 pc/cm3 was measured. According to the model of the electron density distribution in the Galaxy, this value corresponds to a distance of 800 pc.
The paper discusses the fraction of extragalactic cosmic iron nuclei with energies of 1019 eV that reached Earth from distant sources without fragmentation in intergalactic space. It is shown that the fraction of particles with energies E = 1019 eV is significant (about 10
We analyze observations of the pulsar B1508+55 at a frequency of 111 MHz. Five components were identified in the average profile of the pulsar by fitting the profile with a set of Gaussians. In accordance with the classification proposed by Rankin, these components correspond to the emission of two extreme components of the outer cone of emission, two components of the inner cone of emission, and the core. The frequency dependence of the distance separating the maxima of the outer cone components was obtained. Approximation of this dependence by an exponential function in a range of 111 to 408 MHz yields the exponent γ = - 0.54 ± 0.12 . This value is in satisfactory agreement with the predictions for the behavior of the extraordinary X-mode emission. Because of this, we believe that the outer cone of the average profile of the pulsar B1508+55 reflects the emission of the extraordinary mode. Using the traditional model of a hollow cone, the height above the polar cap for the X-mode emission zone at 150 MHz was estimated at R_out = 380 km. The frequency and time scales of diffractive scintillations were obtained: f_dif = 18.0 ± 1.5 Hz and t_dif = 12.6 ± 0.1 s, respectively. Based on our 111-MHz observations and the data available for 327, 408, 640, and 1250 MHz, we built the frequency dependences of fdif and tdif. Fitting the initial parts of these dependencies with a power law yields the values α = 8.2 ± 0.3 and β = 2.1 ± 0.2 for the exponents. These values of the parameters are not consistent with the generally accepted scattering models.
The broadening of radio pulsar pulses caused by scattering on several thin layers of turbulent interstellar plasma is studied. Spatial spectra of inhomogeneities can be anisotropic and different in different layers. We consider two methods for calculating the impulse response function (IRF) that describes the effect of scattering on the pulse shape. The direct method allows us to calculate the IRF for specified model parameters directly from the definition. In the alternative method, the Laplace transform of the IRF is first calculated, and then the inverse Laplace transform is applied to the result. For models with the Gaussian scattering, we developed an algorithm that allows one to derive an explicit expression for the IRF for an arbitrary number of scattering screens. Models with two or more screens and a spatial spectrum of density fluctuations of general form may require complex calculations. A comparative analysis of the computational complexity of the considered approaches has been carried out. Relative simplicity of the implementation of the method based on preliminary calculations of the Laplace transform of the IRF makes it preferable for use in interpreting the results of observations.
Interferometric observations of the star-forming region S255IR in the frequency range 210–250 GHz were carried out with the SMA antenna array. Maps of the region for a large number of molecular lines were built and the spectra of molecular cores SMA1 and SMA2 were obtained. Emission from 53 molecules was detected, including complex organic molecules (COMs) such as CH3CHO, CH3OCH3, CH3CH2CN, and a number of others. The characteristic rotational temperatures in the hot core SMA1 fall within a range of 100–200 K. Estimates of the optical depth in the lines of methanol and some other molecules in the SMA1 and SMA2 cores were made. In the SMA1 core, the optical depth in one of the strongest methanol lines, 5_ - 1-4_ - 1E , was found to be 23.8 ± 1.5 . Based on this value, one can assume that the lines of other COMs, such as CH _3 OCHO, CH3OCH3, CH3CH2OH, which are typically much less abundant in hot cores, in SMA1 are optically thin. Most of the detected molecules can be conditionally split into two groups. Molecules of the first group emit exclusively toward the hot core SMA1, while some or all lines of the second group molecules, in addition to SMA1, emit from a ring-like structure to the west of SMA1. Apparently, this structure is associated with the walls of a cavity formed by high-velocity outflows driven by Young Stellar Objects (YSOs) in the molecular cores SMA1, SMA2, and possibly SMA3. Gas temperature and density in the cavity walls were estimated using methanol lines. The temperature was found to be about 50–60 K, and the density about 107–108 cm–3. The column density of methanol toward the brightness peaks in the lines of this molecule is about 5 × 1015 cm–2. The column densities of other COMs in the ring-shaped structure will be determined in future studies with increased sensitivity achieved by spectral line stacking.
Investigation of various solar wind disturbances and determination of their links to solar sources is essential for improving the accuracy of space weather forecasts. In this study we examine single and complex solar wind structures associated with coronal mass ejections (CMEs) and coronal hole outflows. The study covered the growth period of solar cycle 25 (the year 2023), when a large number of CMEs, including 82 Halo-type events, were observed according to CDAW catalog. Using in situ OMNI data, 33 events were identified (40
The article presents the results of determining the rotation periods, rotation pole coordinates, and stereoform models (hereinafter referred to as forms) of the near-Earth asteroids (NEA): (137126) 1999 CF9, (36183) 1999 TX16, (154029) 2002 CY46, and (154244) 2002 KL6, based on multicolor photometric observations obtained with the SBG telescope of the Kourovka Astronomical Observatory of Ural Federal University. The observations were carried out in the B , V, R , and I filters of the Cousins–Johnson system. The axial rotation periods were estimated using the Lomb–Scargle method followed by approximation of the phase light curves. For each asteroid, light curve inversion method was performed using the same data, which made it possible to construct convex shape models and determine the ecliptic coordinates of the spin axis lying in the region | β| ≲ 30^∘ . The periods obtained lie in the typical NEA range from several to tens of hours. For 2002 CY46 and 2002 KL6, they agree with values reported in the literature. For (137126) 1999 CF9, a rotation period of P = 8.422^h and ecliptic pole coordinates (λ ,β ) = (253^∘ , - 2^∘ ) were obtained. For (36183) 1999 TX16, a solution with period P = 5.57552^h and spin-axis coordinates (λ ,β ) = (69^∘ , + 7^∘ ) was found. For (154029) 2002 CY46, the period is P = 2.56^h with pole coordinates (λ ,β ) = (48^∘ , - 13^∘ ) , and for (154244) 2002 KL6, P = 4.60^h and (λ ,β ) = (38^∘ , + 26^∘ ) .
Within the framework of present-day scenarios for the formation of planets, some conditions governing the development of their satellite systems are considered. By numerical modeling based on the N-body formulation of the three-body problem, the interaction of a planet with a fragment of a circumstellar disk, given in the form of a torus co-orbital of the planet, is studied. As an example, a model of the Solar System is considered in two variants: with a giant planet (Jupiter) and with a terrestrial planet (the Earth). The nature of the interaction of a planet with the material of a disk, which consists of asteroids, comets, and small planetary bodies (ACP objects), determines the status of the planet and its ability to host satellites. The paper discusses two scenarios for the formation of planetary satellites. The first scenario is similar to the formation of planetary systems themselves in circumstellar gas–dust disks that accumulate excess angular momentum from a planet or a star. The second scenario is based on the possibility of a neighboring planet or an asteroid being gravitationally captured into temporary unstable orbits, which are stabilized over time by the loss of excess of their kinetic energy due to collisions with ACP objects, tidal effects from the planet, or the dissipation of excess energy in the circumplanetary gas disk. Theoretical estimates obtained from the analysis of the angular momentum of circumsolar ACPs falling into the Hill sphere of a planet and co-rotating with it show that the formation of a system of its satellites during the accretion of the matter of protoplanetary disks of solar-mass stars is possible only for planets with an orbital semi-major axis exceeding 1 AU. This conclusion highlights the paradox of the Moon, a satellite comparable to the Earth in size, one of the scenarios for the origin of which is proposed in the concept of gravitational capture. The paper discusses the statistics of ACP objects being captured into prograde and retrograde orbits around the planet.
The main goal of this paper is to investigate the motion properties of the eighth smallest body under the effects of seven primary bodies out of which six bodies are placed at the circumference of a circle and seventh body is situated at the center (which is also taken as origin) of the circle. This configuration is known as ring configuration. The mean motion and the equations of motion are determined. Further, numerically the potential surfaces, the locations of equilibrium points, zero-velocity curves, Poincaré surfaces of section, periodic orbits, basins of attractions and the stability of equilibrium points are illustrated for different values of parameter.
We analyze the magnetohydrodynamic (MHD) simulations of the isothermal collapse of protostellar clouds with masses of 1 and 10 1ptM_⊙ and various initial dimensionless ratios of magnetic to gravitational energy, ε_m . Based on the simulations, we study how the mass, size, and angular momentum of primary protostellar disks—magnetostatic structures formed in the early collapse stages and flattened along the cloud’s magnetic field lines—change during the evolution. The analysis shows that the radii of the primary disks increase linearly with ε_m from 400 to 7000 AU for a moderate magnetic field, corresponding to the mean observed values ε_m = 0.1- 0.2 . In this case, the masses of the primary disks range from 0.1 to 0.5 of the cloud’s mass, and their angular momenta lie in the range from 0.05 to 0.2 of the cloud’s initial angular momentum. The growth of the primary disk’s mass and angular momentum with ε_m indicates that these quantities are determined primarily by the mass inflow from the envelope. The mass inflow rate is of 10^ - 4 1ptM_⊙ /year. The magnetic braking of the primary disk dominates over the angular momentum inflow from the envelope in the clouds with a strong magnetic field only, ε_m > 0.4 . In this case, a cloud as a whole evolves into a state of magnetostatic equilibrium, and its angular momentum decreases with increasing ε_m . Our results indicate that the observed scatter in the magnetic field strengths of protostellar clouds should manifest itself in a diversity of the properties of primary protostellar disks and, consequently, result in different star formation scenarios.
A new class of local linear integrals of motion is introduced for two-dimensional rotating systems with the anisotropic effective mass and angular potential. In polar coordinates, a generalized integral analogous to the angular momentum, the existence of which is determined by a specific relationship between the mass function μ (r,θ ) and the potential U(r,θ ) , is constructed. Analytical sufficient conditions for the conservation of the local integral at J = 0 , which link the effective mass μ (r,θ ) , the structural function φ (r,θ ) , and the potential energy U(r,θ ) , are obtained. The fulfillment of these conditions ensures the invariance of the integral in a local region of phase space and establishes criteria for the self-consistency of the dynamical model. We present three analytically solvable examples, demonstrating a wide range of orbital dynamics—from closed orbits to resonant and chaotic regimes. We consider systems with radial–angular modulation of mass, which model the density structures in protoplanetary and accretion disks. The proposed approach is distinguished by its analytical novelty and can serve as a tool for studying stability, identifying resonant structures, and constructing self-consistent models in stellar dynamics and astrophysics. The work is partially based on a report presented at the Modern Stellar Astronomy 2025 conference.
The article presents the results of solar observations during the period of high solar activity in May 2024 using the BSA LPI radio telescope. The solar corona flare activity in our data is manifested by a significant increase in the radiation flux at a frequency of 111 MHz, which is recorded not only in the main lobe of the radiation pattern, but also in distant sidelobes. The increased radio emission turns out to be highly fluctuating in time. It is shown that changes in the radio flux can lag behind changes in the coronal X-ray flux by a day or two.
Formamide (HCONH2) is a pivotal prebiotic molecule, serving as a precursor for the abiotic synthesis of nucleobases. Despite its detection across diverse astrophysical environments, its specific reaction pathways within complex interstellar ices have remained poorly constrained. Here, we report a computational study on the formation of structural isomers of glycine from the radical-radical recombination of formamide and methanol (CH3OH)—abundant interstellar ice constituents—as a potential pathway for synthesizing C2H5NO2 isomers. We identify four distinct C2H5NO2 isomers resulting from the barrierless recombination of primary radicals generated upon radiolysis: the carbamoyl (• 1ptCONH_2 ), formamid-N-yl ( HCONH 1pt •), methoxy ( CH_3O 1pt •), and hydroxymethyl (• 1ptCH_2OH ) radicals. Utilizing high-accuracy composite method (CBS-QB3) calculations and a novel automated conformational analysis algorithm, we determine their relative stabilities and precise adiabatic ionization energies (AIEs). Our results establish methyl carbamate as the most thermodynamically stable product.
Based on the archive data of the RadioAstron project, we analyze observations of the pulsar B1237+25 carried out with the Arecibo radio telescope on February 26, 2018. The observations were performed at a frequency of 327 MHz in the 16 MHz bandwidth in two polarization channels. We study the fine structure of individual pulses by constructing cross-correlation functions (CCFs) between two polarization channels of the receiver (LCP/RCP). This analysis was carried out separately for five different components of the average profile. No microstructure has been found in the averaged CCFs. However, some individual subpulses exhibit the microstructure. The proportion of such subpulses is about 12
Changes in the orbital periods of the eclipsing binaries GS Boo, V442 Cas, and CX Gem are analyzed. It has been shown that variations in the period of each of these systems can be represented by a superposition of the secular decrease and cyclic variations. Cyclic variations in the period can be caused by the presence of a third body in the systems. They can also be a consequence of magnetic activity of the one of GS Boo components and the secondary components of V442 Cas and CX Gem. The secular decrease in the periods of all of these systems can be caused by the angular-momentum loss due to magnetic braking.
The paper presents a comparative analysis of simulations of the magnetosphere of the hot Jupiter HD 209458 b performed with a paraboloid model and with ideal magnetohydrodynamic (MHD) modeling. Two flow regimes around the hot Jupiter—super-Alfvenic and sub-Alfvenic—are considered, since the exoplanet is located near the Alfvén radius. For the super-Alfvenic case, the paraboloid model reproduces a comet-like magnetosphere with closed field lines on the dayside and an elongated tail on the nightside, which is consistent with the results of the MHD modeling (a shock-type intrinsic magnetosphere according to the authors’ classification). In the sub-Alfvenic regime, both models show the formation of pronounced Alfvén wings stretched along the star–planet line for the chosen orientation of the magnetic field of the stellar wind. The fundamental difference between the approaches is emphasized: the paraboloid model efficiently and compactly describes the geometry and topology of the magnetic field (convenient for operational analysis and interpretation of observations), whereas the MHD simulations allow one to account for the interaction of the plasma with the stellar wind and its magnetic field.
The paper presents the results of measurements of the background brightness of the sky in the IR range at the Caucasian Mountain Observatory (CMO) and the Crimean Astronomical Station (CAS) of the Sternberg Astronomical Institute of the Moscow State University (SAI MSU) carried out in 2024–2025. We propose and test a method for taking into account the instrumental background, the contribution of which may exceed the measured signal by factors of tens. The average brightness of the 1-arcsec2 area of the sky at the zenith in the L band is 104 photon/(s m2 nm) ( 5m/arcsec2) for the CMO and 5 × 104 photon/(s m2 nm) ( 3.5m/arcsec2) for the CAS, while in the M band it is 1.7 × 105 photon/(s m2 nm) ( 1.2m/arcsec2) for the CMO and 4 × 105 photon/(s m2 nm) ( 0.2m/arcsec2) for the CAS. It has been shown that the background brightness changes after sunrise by no more than 20 τ_L = 0.09 ± 0.02 and τ_M = 0.33 ± 0.05 at the CMO, and it was τ_L = 0.14 ± 0.05 and τ_M = 0.5 ± 0.1 at the CAS.
