Astronomy Reports最新文献

The problem of motion of a zero-mass point under the influence of attraction to the central body and a small perturbing acceleration ({mathbf{P}}{kern 1pt} ' = {mathbf{P}}{text{/}}{{r}^{2}}) is considered, where (r) is the distance to the attracting center, and components of vector ({mathbf{P}}) are assumed to be constant in a reference system with axes directed along the radius vector, the transversal, and the angular momentum vector. Previously, for this problem, we found equations of motion in the mean elements and formulas for the transition from the osculating elements to the mean elements in the first order of smallness; second-order quantities were neglected. In this study, the Euclidean (root-mean-square over the mean anomaly) displacement norm ({{left| {d{mathbf{r}}} right|}^{2}}) is obtained, where (d{mathbf{r}}) represents the difference between the position vectors on the osculating and mean orbit. It turned out that ({{left| {d{mathbf{r}}} right|}^{2}}) depends only on the components of vector ({mathbf{P}}) (positive definite quadratic form), the semimajor axis (proportional to the second power), and the eccentricity of the osculating ellipse. The norm ({{left| {d{mathbf{r}}} right|}^{2}}) is obtained in the form of series in powers of (beta = e{text{/}}(1 + sqrt {1 - {{e}^{2}}} )) and in powers of the eccentricity (e). The results are applied to the problem of the motion of asteroids under the influence of a perturbing acceleration inversely proportional to the square of the heliocentric distance, in particular, under the influence of the Yarkovsky effect.

The restricted circular three-body problem is studied. All global families of periodic orbits adjacent to the libration points are found. A scenario for the evolution of orbits in the family is given. Chains of global families are highlighted; the chain begins at the triangular libration point, contains global families for the triangular and all collinear libration points, and ends with a family whose orbits are pressed against the main bodies. The evolution of global families in the chain associated with changes in the energy of the system is described. Planar and spatial orbits are studied.

We explore the possibility of using measurements of the gravitational redshift effect as a means to constrain wave dark matter—a class of models in which the dark matter is accounted for by light scalar particles that behave like classical waves. We construct a mathematical framework that is appropriate for clock comparison experiments with remote clocks and can be used to determine the values of the coupling constants of such dark matter with particles of the Standard Model. Using this framework, we consider an experiment to detect dark matter of the Galactic halo using two satellites equipped with accurate and stable atomic clocks and placed into elliptical heliocentric orbits. We demonstrate that, in most cases, the accuracy of this experiment turns out to be not better than that of ground-based experiments with colocated clocks. The limitation of the accuracy of the space-based experiment is found to be due to the non-relativistic Doppler compensation system, required when using moving clocks, which decreases the amplitude of the useful signal. Possible solutions to this problem are discussed.

The kinematics of the ϵ Cha young stellar association close to the Sun has been studied based on a list of candidate stars from the Dickson-Vandervelde et al. work. The working sample consists of 26 stars with parallaxes, proper motions from the Gaia DR3 catalog and radial velocities taken from literary sources. The orbits of the stars back to the past were constructed, and the moment when the association had a minimum spatial size was determined, as well as an analysis of the dependencies of the velocities (U,;V,;W) on the coordinates (x,;y,;z) was carried out. It is shown that the initial sample is divided into two parts with different kinematic properties. The first sample included 9 stars. Based on the construction of the orbits of these 9 stars, an age estimate of (t = 4.9 pm 0.8) million years was obtained. An expansion coefficient in the (xz) plane with the value ({{K}_{{xz}}} = 135 pm 19) km/s/kpc was also found for them, on the basis of which another age estimate (t = 7.2 pm 1.0) Ma was obtained. The second sample included 17 stars. The construction of their orbits gave an estimate of age (t = 0.2 pm 0.3) Ma, and based on the gradient (dW{text{/}}dz = 707 pm ) 248 km/s/kpc, a second estimate of their age (t = 1.4 pm 0.5) Ma was obtained. This suggests that the (epsilon ) Cha association either consists of two groupings of different ages, or a younger one arose as a result of a recent outbreak of star formation within a common star system. The question of the gravitational connection of the groupings has not been considered in the framework of this work.

Geomagnetic storms have a significant impact on the performance of technical systems both in space and on Earth. The sources of strong geomagnetic storms are most often interplanetary coronal mass ejections (ICMEs), generated by coronal mass ejections (CMEs) in the solar corona. The ICME forecast is based on regular optical observations of the Sun, which make it possible to detect CMEs at the formation stage. It is known that the intensity of geomagnetic storms correlates with the magnitude of the southern component of the magnetic field (B_z) of the ICME. However, it is not possible yet to predict the sign and magnitude of B_z from solar observations for the operational forecast of an arbitrary CME. Under these conditions, a preliminary forecast of the magnetic storm probability can be obtained under the assumption that the strength of the storm is related to the magnitude of the magnetic flux from the eruption region, observed as dimming. In this paper, we examine the relationship between the integral magnetic flux from the dimming region and the probability that CMEs associated with them will cause geomagnetic storms, using a series of 37 eruptive events in 2010–2012. It is shown that there is a general trend toward an increase in the ICMEs geoefficiency with an increase in the magnitude of the magnetic flux from the dimming region. It has been demonstrated that the frequency of moderate and severe storms observation increases in cases of complex events associated with the interaction of CMEs with other solar wind streams in the heliosphere.

We investigate unresolved binary systems with components of main sequence star (MS) and white dwarf (WD) in nine open clusters. These systems are located below and to the left of the main sequence on the color-magnitude diagram. We compare the number of cluster stars that have likely evolved into white dwarfs with the number of candidates for unresolved binary systems with WD. The number of probable cluster members lying below the main sequence, is generally less than the expected number of WDs. The observations in the ultraviolet could detect WDs and unresolved binary WD+MS systems more confidently than the observations in the visible range.

The B1133+16 pulsar was observed at a frequency of 111 MHz with the BSA radio telescope of the Pushchino Radio Astronomy Observatory from October 2022 to March 2023. Observations were conducted twice a week for two consecutive days. In total, 38 measurements of the scintillation parameters were carried out with a high frequency resolution (up to 65 Hz). We used continuous signal recording in the frequency band of 2.5 MHz. The signal was reconstructed using the coherent dedispersion method. The pulsar’s dynamic spectra (DSP) were analyzed using the two-dimensional autocorrelation function (2DACF). The fine frequency structure of the pulsar’s scintillation was investigated both through the analysis of time and frequency sections of 2DACF from DSP and through the spectra of individual pulses. The analysis of the frequency sections of the 2DACF showed that the true form of diffractive frequency distortions can be represented by a generalized exponential function with a characteristic frequency width of 1.2 kHz and an index of 0.57. Comparison of scintillation parameters separately for two components of the average profile showed that they are identical for both components.

In the article, we have studied the impact linear polarization of the helium D₃ line that takes place in the solar chromosphere under the action of protons accelerated in solar flares. The dependence of the energy distribution of protons on the distance traveled inside the chromosphere is calculated. The ratio of the concentrations of nonthermal protons and thermal electrons at different depths is theoretically determined. From the calculation of the degree of linear polarization of the helium line D₃ for different layers of the chromosphere, the region of probable formation of the line is determined.

It is known that so-called solar flares systematically occur in the area of sunspots. They are accompanied by radiation in almost all frequency ranges and sometimes by the emission of hot plasma. Observations on the RATAN-600 radio telescope have shown that the radio emission spectrum of plasma clouds heated to values of the order of 10⁶ K erupted from the solar flare region turned out to be adiabatic. The high correlation of the inhomogeneities of the radio emission spectra of active formation over a group of sunspots indicates the stable presence of recombination radio lines in the radiation of active formation. However, the radio emission spectra of hot plasma clouds ejected from the region of solar flares occurring in this group of spots do not show any correlation.

Several new models of a layered inhomogeneous elliptical galaxy (EG) having the shape either a triaxial ellipsoid or an oblate or prolate spheroid and consisting of baryonic mass and dark matter with different laws of density distribution—profiles. Based on these models, some key dynamic parameters of the EG were determined: gravitational (potential) energy and rotational kinetic energy, total surface brightness, total luminosity, and velocity dispersion depending on the distance to the EG center. The relationships between the important dynamic parameters of the galaxy have been established: “mass–dimensions”, “mass–velocity dispersion”, “size–dispersion speeds–luminosity” (surface brightness). Evolutionary scenarios for the formation of EG were studied according to these models. The results obtained were applied to sixty model EGs with parameters exactly matching those that actually exist and are presented in the form of tables.