Astronomy Reports最新文献

{"title":"The Probable Quadruple Systems GI Cep and V548 Cyg","authors":"A. I. Khaliullina","doi":"10.1134/S1063772925701951","DOIUrl":"10.1134/S1063772925701951","url":null,"abstract":"<p>Orbital-period variations of the eclipsing binaries GI Cep and V548 Cyg are analyzed. The period variations in both systems can be described as a superposition of secular decrease and two cyclic variations of the period. The rate of decrease of the period d<i>P</i>/d<i>t</i> = 3.73 × 10^–7 day/yr for GI Cep and 2.38 × 10^–7 day/yr for V548 Cyg. A superposition of two types of cyclic variations is observed for GI Cep and V548 Cyg: with periods 14.4 years and 33.7 years for GI Cep, and 5.4 and 43.8 years for V548 Cyg. The observed cyclic variations in the period of GI Cep can occur due to the presence of a third body in the system or due to the magnetic activity of the secondary component. The system can be triple or quadruple. The hypothesis of magnetic activity is not suitable for V548 Cyg. Apparently, this is quadruple system.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 7","pages":"581 - 590"},"PeriodicalIF":0.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics of Super-Earths and Mini-Neptunes","authors":"G. A. Morozov,&nbsp;E. S. Belenkaya","doi":"10.1134/S1063772925701926","DOIUrl":"10.1134/S1063772925701926","url":null,"abstract":"<p>More than half of currently known stars have nearby exoplanets with size between Earth and Neptune, called super-Earths and mini-Neptunes. The California–Kepler Survey (CKS) studied data from NASA’s Kepler mission and revealed a bimodal distribution of planets with <span>(R &lt; 3.5{kern 1pt} {{R}_{{text{E}}}})</span> by radius (<span>({{R}_{{text{E}}}})</span> is the radius of the Earth). It occurred that there was a lack of planets with radii <span>(1.5{kern 1pt} {{R}_{{text{E}}}} &lt; R &lt; 2{{R}_{{text{E}}}})</span>. The CKS did not take into account data from other missions and exoplanets discovered by non-transit methods. All data from this mission were limited to 2022. This article examines the distribution of super-Earths and mini-Neptunes, taking into account all data on exoplanets known by 2024 from the NASA catalog. Mini-Neptunes and super-Earths with known radii were selected. There were 937 such planets, including 366 planets with known mass. Since the radius of a planet can only be determined by the transit method, the distribution by radii is built using the data of transit planets, but, unlike CKS, not only the data of the Kepler mission are taken. The data for the remaining distributions are selected regardless of the method of their detection and the telescope used. We show that the current data are best fitted by a double-peaked Gaussian distribution, which describes two populations of planets: rocky (hereinafter super-Earths) and exoplanets with gas envelopes (exoplanets surrounded by hydrogen–helium atmospheres, but consisting mainly of heavy elements—ice and rock, hereinafter mini-Neptunes). The magnitude of the gap between populations at present is analyzed. It is shown that the gap is filled evenly on both sides; in CKS, the first peak is significantly smaller than the second, that is, there were fewer super-Earths than mini-Neptunes. Perhaps more super-Earths have been discovered recently, which is why there was a shortage of them in the CKS. The composition of some exoplanets was determined using theoretical models of the dependence of mass on radius.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 7","pages":"574 - 580"},"PeriodicalIF":0.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S1063772925701926.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nature of Quasi-Periodic Radiative Pulsations in the Rope Flux Models of Flares","authors":"A. A. Solov’ev","doi":"10.1134/S106377292570194X","DOIUrl":"10.1134/S106377292570194X","url":null,"abstract":"<p>Rope flux models of solar flares associate the phenomenon of quasi-periodic pulsations of flare radiation with a parametric catastrophe that occurs when the top of a twisted magnetic loop enters the corona. A sharp decrease in external pressure leads to the longitudinal magnetic field of a force-free flux rope tending to zero on the magnetic surface where the current changes sign, and the density of the azimuthal current and the force-free parameter begin to grow indefinitely near this surface, approaching a break. The current velocity of electrons here will inevitably exceed the speed of ion sound, and plasma instability will arise. Scattering of electrons on ion-acoustic plasmons will sharply decrease the plasma conductivity and cause rapid, flare dissipation of the magnetic energy of the rope, i.e., decrease in the amplitude of the field and currents and expansion of the rope cross-section. This is how the first peak of the flare radiation will be formed. In this case, the torque applied to each section of the rope will be greatly weakened in the energy release region. In equilibrium, the torque should be the same along the entire length of the loop, so there will be a transfer of the azimuthal flux by Alfvén waves from the loop legs to the top. Alignment of the torque along the rope axis will return the rope to its original state, after which the second peak of the flare radiation is formed, and the process is repeated several times until the reserve of free magnetic energy associated with the currents in the entire loop decreases significantly. The oscillations of the rope cross-section accompanying the peaks of its radiation represent a specific type of fluctuations of a system with time-varying rigidity: in them the magnetic field intensity, providing the restoring force, changes greatly. Calculation of such oscillations allows achieving not only qualitative but also quantitative correspondence between the theoretical results and observational data.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 7","pages":"622 - 632"},"PeriodicalIF":0.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stellar Critical Parameters in the Uniform Density Approximation","authors":"G. S. Bisnovatyi-Kogan,&nbsp;E. A. Patraman","doi":"10.1134/S1063772925701914","DOIUrl":"10.1134/S1063772925701914","url":null,"abstract":"<p>Stellar models are calculated in the approximation of a uniform density distribution. Variational method was used for determination of the boundary of a stability loss, for stellar masses in the range from 2 up to <span>({{10}^{5}}{kern 1pt} {{M}_{ odot }})</span>. The effects of the general relativity had been taken into account. The equation of state in the temperature and density ranges <span>({{10}^{9}} &lt; T{{ &lt; 10}^{{10}}})</span> K, <span>({{10}^{5}} &lt; rho {{ &lt; 10}^{{10}}})</span> g/cm³ had been taken from the work of Imshennik and Nadyozhin (1965). The critical parameters for the values of entropy and stellar masses differ from more accurate values, obtained using a more complicated variant of accepted density distribution, not more than 12%.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 7","pages":"563 - 573"},"PeriodicalIF":0.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Search for Orientation Effects in the Stellar Winds of Wolf–Rayet Stars","authors":"A. M. Cherepashchuk,&nbsp;I. A. Shaposhnikov","doi":"10.1134/S1063772925701975","DOIUrl":"10.1134/S1063772925701975","url":null,"abstract":"<p>The results of the study of the correlation between the Doppler widths (FWHM) of emission lines in the spectra of close and some wide binary systems of the WR + OB type and the system’s orbit inclination are presented in order to search for the effects of the orientation of the WR stellar wind. The widths of the studied lines do not show a correlation with the orbital inclination, and no significant orientation effects for the WR wind were detected.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 7","pages":"591 - 608"},"PeriodicalIF":0.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the Thermal Structure of a Protoplanetary Disk Using Multiband Flux-Limited Diffusion Approximation","authors":"Ya. N. Pavlyuchenkov,&nbsp;V. V. Akimkin","doi":"10.1134/S1063772925701938","DOIUrl":"10.1134/S1063772925701938","url":null,"abstract":"<p>This work continues the analysis of the model for calculating the thermal structure of an axisymmetric protoplanetary disk, initiated in the paper by Pavlyuchenkov (2024). The model is based on the well-known Flux-Limited Diffusion (FLD) approximation with separate calculation of heating by direct stellar radiation (hereinafter referred to as the FLD^s method). In addition to the previously described FLD^s model with wavelength-averaged opacities, we present a multiband model mFLD^s, where the spectrum of thermal radiation is divided into several frequency bands. The model is based on an implicit finite-difference scheme for the equations of thermal radiation diffusion, which reduces to a system of linear algebraic equations written in hypermatrix form. A modified Gauss method for inverting the sparse hypermatrix of the original system of linear equations is proposed. The simulation results described in the article show that the midplane radial temperature profile obtained with the mFLD^s method has a variable slope in accordance with the reference Monte Carlo radiative transfer simulations. The mFLD^s model also qualitatively reproduces the non-isothermality of the temperature distribution along the angular coordinate near the midplane, which is not provided by the FLD^s method. However, quantitative differences remain between the reference temperature values and the results of mFLD^s. These differences are likely due to the diffusive nature of the FLD approximation. It is also shown that the characteristic times for the disk to reach thermal equilibrium within the mFLD^s model can be significantly shorter than in FLD^s. This property should be taken into account when modeling non-stationary processes in protoplanetary disks within FLD-based models.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 7","pages":"547 - 562"},"PeriodicalIF":0.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics of Exoplanets in Transiting Systems HD 189733 and HD 209458: Considering the Four-Parameter Law of Star Darkening within the Framework of a Three-Dimensional Model of Its Atmosphere","authors":"E. V. Bekesov","doi":"10.1134/S1063772925701963","DOIUrl":"10.1134/S1063772925701963","url":null,"abstract":"<p>The paper presents an analysis of high-precision satellite light curves of exoplanets HD 189733b and HD 209458b. The dependence of the exoplanet radius on the wavelength caused by scattering in the planetary atmosphere is determined using a four-parameter limb darkening law based on a three-dimensional model of the stellar atmosphere. It is shown that when using the same exoplanet system characteristics for all wavelengths, primarily the orbital inclination, as well as when using a four-parameter law with a refined radius of the star, the change in the radius of the exoplanet HD 189733b with increasing corresponds to the model of an exponential Rayleigh atmosphere with a characteristic height of 380–400 km. At the same time, the characteristics of the atmosphere of HD 209458b largely depend on the adopted eccentricity of the system.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 7","pages":"609 - 621"},"PeriodicalIF":0.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics of Non-Kolmogorov Atmospheric Optical Turbulence in Terms of High-Resolution Astronomical Observations","authors":"A. Yu. Shikhovtsev,&nbsp;P. G. Kovadlo","doi":"10.1134/S1063772925701902","DOIUrl":"10.1134/S1063772925701902","url":null,"abstract":"<p>This paper is considers the structure of atmospheric optical turbulence using both measurements in the atmospheric surface layer and modeling data for the entire optically active atmosphere. Estimates of the structural characteristics of Kolmogorov and non-Kolmogorov atmospheric optical turbulence are presented. Approaches to calculating atmospheric coherence lengths are discussed, including the Fried parameter, the Bump length, and the coherence lengths of non-Kolmogorov optical turbulence sensitive to deformations of the energy spectrum of turbulent air temperature fluctuations. Estimates of the atmospheric angular resolution in the daytime for the location of the Large Solar Vacuum Telescope are given. The developed methodological foundations for calculating the characteristics of optical turbulence and atmospheric angular resolution can be applied to other astronomical observatories (both solar and stellar).</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 6","pages":"510 - 518"},"PeriodicalIF":0.7,"publicationDate":"2025-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tayler Instability of Magnetic Field as the Possible Reason for the Period Changes in Ap Star 56 Ari","authors":"I. S. Potravnov,&nbsp;L. L. Kitchatinov","doi":"10.1134/S1063772925701872","DOIUrl":"10.1134/S1063772925701872","url":null,"abstract":"<p>The physical mechanism responsible for the photometric period changes in chemically peculiar star 56 Ari was searched. It was previously shown that rate of the star’s period increase is several orders of magnitude larger than the rates expected from the evolutionary changes of the angular momentum or due to magnetic braking. Also no secular changes were detected in the surface structure or visibility of chemical spots which are responsible for the rotational modulation of stellar brightness. We hypothesize that period changes in 56 Ari are caused by the drift of surface magnetic and associated abundance structures as a result of the kink-type (Tayler) instability of the background magnetic field in the radiative zone of the star. Results of the numerical simulation presented in the paper yield growth and drift rates of the most rapidly developing non-axisymmetric mode of the instability, consistent with the observed rate of period changes in 56 Ari. The surface geometry of the 56 Ari magnetic field is also reproduces in the calculations. The proposed mechanism may also be used to explain the character of period changes in other Ap/Bp stars demonstrating such an effect.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 6","pages":"500 - 509"},"PeriodicalIF":0.7,"publicationDate":"2025-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Average Temporal Profiles of Solar Flare Microwave Emission: Morphology and Application","authors":"I. D. Motyk,&nbsp;L. K. Kashapova,&nbsp;D. V. Rozhkova","doi":"10.1134/S1063772925701860","DOIUrl":"10.1134/S1063772925701860","url":null,"abstract":"<p>Both solar and stellar average temporal profiles of emission demonstrate general laws of evolution of such complex and diverse phenomenon as flare. Empirically obtained average profiles for events with simple dynamic make it possible both to analyze the emission mechanisms of solar and stellar flares and to help to divide complex events into discrete acts of energy release. Microwave emission is of particular interest, since it can reflect the precipitation dynamics of accelerated electrons. For the reconstruction of average time profiles. We selected 116 observed with the Siberian Radioheliograph observations in the range of 3‒24 GHz. These profiles have demonstrated a simple time structure and a broadband gyrosynchrotron spectrum of non-thermal nature. The wide spectral range allowed to divide emission into emission of optically thick and optically thin sources. The time profiles that describe the emission from different regions of the flare loop have been summed within the respective spectral band, after which for each event, normalization and time scaling have been applied. The average time profiles have been obtained as the median value for each time bin (step). As a result, it has been shown that the microwave average time profiles for the microwave optically thick and thin sources are identical for a solar flare with simple dynamics. This indicates the dominance of accelerated electron precipitation processes in the emission of such events. Also, the dominance of non-thermal processes for this type of event has been confirmed by a comparison with the results of a solar-flare dynamics modelling in the 304 Å line obtained in studies of other authors and an analysis of the dynamics of microwave emission during the decay phase. Analytical functions that describe the rise and decay phases of microwave emission of solar-flare have been obtained. The use of analytical functions in combination with the average time profile for the analysis of the February 3, 2022 event has shown the possibility of using this method to separate the acts of energy release associated with the precipitation of accelerated electrons. The obtained average time profiles, as well as analytical functions describing the behaviour of simple solar-flare microwave emission, can be used both to analyze the emission of solar events in the microwave range and to study the processes occurring during stellar flares.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 6","pages":"519 - 531"},"PeriodicalIF":0.7,"publicationDate":"2025-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}