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卷 102, 编号 1 (2025)
Articles
ON THE STABILITY OF A LAYERED INHOMOGENEOUS ELLIPTICAL GALAXY AS DYNAMIC SYSTEM
摘要
In this paper, we consider 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 (BM) and dark matter (DM) 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, angular momentum distribution and specific angular momentum depending on density profiles. The equilibrium and stability (instability) of the EG as a dynamic system have been established according to known criteria. Critical values found parameters of the family of spheroids that determine the boundaries of stability (or instability) dynamic system based on the values of specific angular momentum depending on the density profiles. 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 and figures.
Astronomičeskij žurnal. 2025;102(1):3-22
3-22
LIGHT CURVE SYNTHESIS FOR COLLIDING WIND BINARY SYSTEMS
摘要
The synthesis method which allows one to compute light curves of binary systems in the Roche model is a powerful and widely used analysis tool. However, in its original form, it is not suitable for the analysis of light curves of binary systems in which one or both components have powerful stellar winds. Previously, we proposed a model of a binary system based on the synthesis method and including one component with a wind. In the current paper, we propose a generalization of the model to the case when both components of the binary system have winds. The surface separating the two winds (the contact surface) is calculated within the framework of a steady state model of stellar wind collision. When calculating the light curve, the absorption of stellar radiation in the winds, as well as in the cooling layers located on both sides of the contact surface, is taken into account. The structure of the cooling layers and their surface density are calculated in the radiative shock limit. The algorithm allows one to take into account the asymmetry of the contact surface caused by the Coriolis force, as well as (using pre-calculated tables) the radiative inhibition of the winds in close binary systems. The results of numerical calculations in various test models are presented, clearly demonstrating the need to take into account the influence of the winds on optical light curves in WR + WR, WR + O, O + O systems.
Astronomičeskij žurnal. 2025;102(1):23-34
23-34
3D NUMERICAL MODEL FOR STUDYING ELECTRON PRECIPITATION IN THE UPPER ATMOSPHERES OF VENUS-LIKE EXOPLANETS
摘要
The paper presents a three-dimensional numerical model of solar wind plasma flow around a terrestrial planet that does not have its own magnetic field. The model is based on the approximation of multicomponent magnetohydrodynamics and takes into account ionization and recombination processes. The numerical model is validated using the example of the magnetosphere of Venus. Our model, in particular, allows us to calculate the structure and parameters of electron precipitation into the planet’s ionosphere. The developed model is supposed to be used to study observational manifestations of the potential biomarker NO in the atmospheres of exoplanets without their own magnetic field.
Astronomičeskij žurnal. 2025;102(1):35-48
35-48
ACTIVITY OF THE STAR TOI-1408 AND MASS LOSS BY THE ATMOSPHERES OF ITS EXOPLANETS
摘要
We considers the properties of the multiplanetary system TOI-1408, consisting of a hot Jupiter (planet (b), (1.86 ± 0.02) 𝑀Jup, (2.4 ± 0.5) 𝑅Jup) and a sub-neptune (planet (c), (2.22 ± 0.06) 𝑅⊕, (7.6 ± 0.2) 𝑀⊕) orbiting a star of spectral class F. Measurements of radial velocities indicate the existence of an additional celestial body with an orbital period of several thousand days. The TOI-1408 system makes it possible to study the migration processes of hot Jupiter-type planets in cases where a less massive planet (c) is closer to the star than a more massive one (b). Based on archival measurements of the TOI-1408 brightness (DASCH project), we made estimates of the length of the possible cyclic long-term variability of the object (equal to about 10 500 days). The analysis of the brightness variability of TOI-1408 according to the Kamogata Wide-field Survey (KWS) archive led to the detection of peaks in the power spectrum corresponding to a rotation period of about 7.5 days. Estimates of the mass loss of the planets atmospheres were obtained, which were established for two values of the parameter log 𝑅'HK (-4.94 and -4.59) corresponding to the maxima of the bimodal distribution of this parameter for low and high activity for stars of spectral class F. The mass loss of planet (b) (hot Jupiter) can reach 2.3 × 1011 g/s, and of the sub-neptune - planet (c) - 2.7 × 1010 g/s for the value log 𝑅'HK = -4.59. The obtained data are in good agreement with the results for exoplanets of the corresponding types (including for hot Jupiter HD 189733 b and warm Neptune GJ 436 b).
Astronomičeskij žurnal. 2025;102(1):49-52
49-52
ACCELERATION POTENTIAL AND DENSITY PROFILE OF SECONDARY PLASMA IN THE MAGNETOSPHERE OF ORTHOGONAL PULSARS
摘要
A new method for determining the accelerating potential above the polar caps of radio pulsars with an arbitrary inclination angle of the magnetic axis to the rotation axis is proposed. The approach is based on the concept of a vacuum gap, the height and shape of the upper boundary of which are found self-consistently together with the solution of the corresponding Poisson equation. In turn, knowledge of the accelerating potential allows one to determine the transverse profiles of the secondary plasma density. It is also shown that the influence of inverse Compton scattering on the processes under consideration is insignificant.
Astronomičeskij žurnal. 2025;102(1):53-65
53-65
THE DIFFERENT FACTORS INFLUENCE ON THE SOLAR FLARES ENERGY
摘要
The factors influencing the energy of the solar flare are being studied. The model of particle acceleration in the magnetic X-singularity is investigated. It was found that the flare energy depends mainly on the flow of electrons into the acceleration zone. The change in such a flow is determined by the size of the acceleration zone. It is calculated that for a chromospheric flare source the vertical length of the acceleration zone varies from ∼100 km to ≈ 2 ⋅ 103 km and its diameter varies from ∼1 km to ≈ 100 km.
Astronomičeskij žurnal. 2025;102(1):66-70
66-70
DISPLACEMENT NORM IN THE PRESENCE OF AN INVERSE-SQUARE PERTURBING ACCELERATION IN THE REFERENCE FRAME ASSOCIATED WITH THE VELOCITY VECTOR
摘要
The problem of motion of a zero-mass-point under the action of attraction to the central body and a small perturbing acceleration P′ = P/𝑟2 is considered, where 𝑟 is the distance to the attracting center and components of the vector P are assumed to be constant in a reference system with the axes directed along the velocity vector, the main normal and the angular momentum vector. Previously, for this problem, equations of motion in the mean elements and formulas for the transition from osculating elements to the mean ones in the first order of smallness were found; second-order quantities are neglected. If the perturbing forces are small, then the osculating orbit slightly deviates from the mean one. The difference 𝑑r between the position vectors on the osculating and mean orbit is a quasi-periodic function of time. In this work, the Euclidean (root-mean-square over the mean anomaly) norm ∥𝑑r∥2 of the displacement of the osculating orbit relative to the mean one is obtained. It turned out that ∥𝑑r∥2 depends only on the components of the vector P (positive definite quadratic form), the semi-major axis (proportional to the second power) and the eccentricity of the osculating ellipse. The norm ∥𝑑r∥2 is obtained in the form of series in powers of eccentricity 𝑒. The resulting expression holds up to 𝑒0 ≈ 0.995862; for 𝑒 > 𝑒0, ϱ = √∥𝑑r∥2 can take complex values. The results are applied to the problem of the motion of model bodies under the action of perturbing acceleration caused by the Yarkovsky effect. A comparison of the results with similar ones for the norm ∥𝑑r∥2 in the reference system associated with the radius vector was also carried out.
Astronomičeskij žurnal. 2025;102(1):71-82
71-82