Astronomy Reports最新文献_第5页

Spottedness and Flare Activity of Solar-Type Stars with Exoplanets 太阳型恒星与系外行星的斑点和耀斑活动

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-22 DOI: 10.1134/S1063772925701768

I. S. Savanov

引用次数: 0

Data Analysis of the Characteristics of the Most Powerful Discrete Radio Sources Used in Gain Measurements of Large Antennas by Radio Astronomy 大型天线增益测量中最大功率离散射电源特性的射电天文学分析

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-22 DOI: 10.1134/S1063772925701720

N. A. Dugin, A. V. Kalinin

引用次数: 0

Rayleigh Laser Guide Star for the Zeiss-2000 Telescope at the Terskol Peak Observatory Terskol峰天文台蔡司-2000望远镜的瑞利激光导星

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-22 DOI: 10.1134/S1063772925701719

L. A. Bolbasova, E. A. Kopylov, A. V. Larichev, N. G. Iroshnikov, M. E. Sachkov

引用次数: 0

Entropic Cosmology Based on Kaniadakis Dual Entropy on the Cosmological Horizon of the Universe 基于卡尼达基斯对偶熵的宇宙视界的熵宇宙学

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-22 DOI: 10.1134/S1063772925701744

A. V. Kolesnichenko

{"title":"Entropic Cosmology Based on Kaniadakis Dual Entropy on the Cosmological Horizon of the Universe","authors":"A. V. Kolesnichenko","doi":"10.1134/S1063772925701744","DOIUrl":"10.1134/S1063772925701744","url":null,"abstract":"Within the framework of entropic cosmology, several variants of a model describing the evolution of the Universe are considered, based on the Friedmann–Robertson–Walker (FRW) system of equations reconstructed taking into account a new modification of the Kaniadakis entropy at the cosmological horizon. The modification is carried out by replacing the Bekenstein–Hawking entropy in the dual expression of the Kaniadakis entropy (in which all states have the same probability) by the Barrow entropy associated with the transformation of the horizon of the Universe surface due to quantum-gravitational effects. As a result, various cosmological scenarios of the accelerated expansion of the Universe on the basis of the reconstructed FRW equations containing an additional force term depending on two free parameters of the model are obtained: the deformation parameter κ of the Kaniadakis entropy, which is responsible for taking into account the peculiarities of space-time, due to the long-range nature of gravitation, and the deformation parameter κ of the Barrow entropy, which is responsible for the fractal structure of the cosmological horizon surface, associated with the action of gravitational-quantum effects. The presence of two free parameters allows us to obtain new variants of driving forces in the FRW equations, which cause a deviation from the “standard” Bekenstein–Hawking holographic model and thus lead to a more accurate approximation to reality. The proposed approach meets the known requirements for thermodynamic modeling of the dynamical evolution of the Universe without involving the concept of hypothetical dark energy and based on the use of anti-gravity entropic forces. The obtained results show that the proposed entropic formalism can open additional opportunities for deeper insight into the nature of space-time and fractal properties of the Universe horizon.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 4","pages":"308 - 323"},"PeriodicalIF":0.7,"publicationDate":"2025-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145167343","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}

引用次数: 0

Gas-Dynamic Instabilities in a Two-Dimensional Boundary Layer during Accretion onto Compact Star 致密恒星吸积过程中二维边界层的气体动力学不稳定性

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-22 DOI: 10.1134/S1063772925701707

A. G. Aksenov, V. M. Chechetkin

{"title":"Gas-Dynamic Instabilities in a Two-Dimensional Boundary Layer during Accretion onto Compact Star","authors":"A. G. Aksenov, V. M. Chechetkin","doi":"10.1134/S1063772925701707","DOIUrl":"10.1134/S1063772925701707","url":null,"abstract":"The purpose of the study has been to build a self-consistent gas-dynamic model of the accretion disk of a compact astrophysical object with allowance for viscosity. The matter falling on a compact object consists of proton gas, electrons, and radiation arising from the braking of a rotating gas at a speed comparable to light one. Physical proton viscosity is not sufficient in the gas-dynamic accretion model with laminar flow. It is necessary to introduce the so-called turbulent viscosity probably arising from the development of instabilities to explain the loss of the disk angular momentum. With a quantitative mathematical model of gas dynamics with allowance for the generally accepted turbulent viscosity, we want to demonstrate a solution with such instability. In a recently published study on Kepler disk braking, we have been able to obtain only large-scale vortex structures arising from azimuthal perturbations, for example, due to tidal effects and demonstrated an increase in disk braking against a neutron star due to these vortex structures. While the development of small-scale shear instability on the surface of a neutron star for a Kepler disk has not been demonstrated in calculations. In this study, we have examined a non-Keplerian disk with a non-zero negative radial velocity ensuring the flow of matter to the surface of a compact star, as a result of which shear instability and turbulence appear.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 4","pages":"269 - 279"},"PeriodicalIF":0.7,"publicationDate":"2025-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168432","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}

引用次数: 0

Detection of Radio Emissions from Magnetar RX J1605.3+3249 at Frequency of 111 MHz 磁星RX J1605.3+3249在111兆赫频率下的无线电发射探测

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-22 DOI: 10.1134/S1063772925701756

A. E. Rodin, V. A. Fedorova

引用次数: 0

On Estimating the Masses of the Components of Visual Binary Systems 关于视觉双星系统分量质量的估计

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-11 DOI: 10.1134/S1063772925701689

A. Yu. Sytov, O. Yu. Malkov

引用次数: 0

Efficient Computations in Keplerian Motion and Kepler’s Equation 开普勒运动和开普勒方程的有效计算

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-11 DOI: 10.1134/S1063772925701653

I. A. Moiseev, N. V. Emelyanov

引用次数: 0

Observations of the Magnetar XINS 1308.6+2127 on the BSA LPI Radio Telescope 磁星XINS 1308.6+2127在BSA LPI射电望远镜上的观测

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-11 DOI: 10.1134/S1063772925701677

A. E. Rodin, V. A. Fedorova

引用次数: 0

Study of the High Braking Index of Pulsar PSR J1640–4631 by the Combination of Magnetic Dipole and Gravitational Wave Radiation 磁偶极子与引力波辐射联合研究脉冲星PSR J1640-4631的高制动指数

IF 0.7 4区物理与天体物理

Astronomy Reports Pub Date : 2025-06-11 DOI: 10.1134/S1063772925701628

Shu Ma, Dehua Wang, Chengmin Zhang, Erbil Gügercinoğlu, Xianghan Cui, Zhiyao Yang, Yungang Zhou

{"title":"Study of the High Braking Index of Pulsar PSR J1640–4631 by the Combination of Magnetic Dipole and Gravitational Wave Radiation","authors":"Shu Ma, Dehua Wang, Chengmin Zhang, Erbil Gügercinoğlu, Xianghan Cui, Zhiyao Yang, Yungang Zhou","doi":"10.1134/S1063772925701628","DOIUrl":"10.1134/S1063772925701628","url":null,"abstract":"The braking index of a pulsar is a key parameter for understanding its radiation characteristics and kinetic energy loss mechanisms. The magnetic dipole radiation (MDR) model predicts a constant value for the braking index (n = 3), as described by a power-law form of the stellar spin-down between the spin angular frequency ((Omega )) and its derivative as ( - dot {Omega } propto {{Omega }^{{n = 3}}}). However, the timing observations indicate that the pulsar PSR J1640–4631 has an unusually high braking index of (n = 3.15 pm 0.03), which is unlike the other pulsars with precisely measured index in between 1 and 3. Therefore, the spin-down of this pulsar should not be controlled by the standard MDR model itself, thus we consider the gravitational wave radiation (GWR) induced by the deformed neutron star to have a contribution, however, which predicts the braking index (n = 5). Thus, we applied the combination of MDR and GWR to explain the higher braking index than 3, and then found that the (n) value is not a constant, but evolves from 5 to 3 with time. We also derived the evolution formula of the braking index and spin period ((P = 2pi {text{/}}Omega )), and their evolution simulations are also presented by assuming the initial spin period of this pulsar to be 1, 10 and 20 ms, respectively. Furthermore, the particular properties of the pulsar PSR J1640–4631 are discussed, and as a comparison, the stellar spin evolution with the constant spin-down power-law index (n = 3.15) is also thoroughly investigated.","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"69 3","pages":"205 - 214"},"PeriodicalIF":0.7,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145163970","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}

引用次数: 0