Astrophysics and Space Science最新文献_第6页

Numerical model of fast electron energy deposition in interstellar molecular gas 星际分子气体中快速电子能量沉积的数值模型

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-06-26 DOI: 10.1007/s10509-026-04597-x

Aleksandr Nesterenok

{"title":"Numerical model of fast electron energy deposition in interstellar molecular gas","authors":"Aleksandr Nesterenok","doi":"10.1007/s10509-026-04597-x","DOIUrl":"10.1007/s10509-026-04597-x","url":null,"abstract":"<div><p>The energy deposition of fast electrons in interstellar molecular gas is considered. We use the rotationally resolved cross sections for electron-impact excitation of H<sub>2</sub> molecule that were calculated using the adiabatic-nuclei molecular convergent close-coupling method. The initial electron energy distribution is assumed mono-energetic, and the differential equation for electron energy distribution is solved. We compare calculated energy deposition parameters with the results of similar studies in which the Monte Carlo approach was used. It is shown that about 11 per cent of the initial energy of fast electrons goes into direct ro-vibrational excitation of energy levels of H<sub>2</sub> molecule including pure rotational excitation in neutral molecular gas. About 7 per cent of initial electron energy goes into the excitation to <span>(v=1)</span> vibrational state of H<sub>2</sub> molecule, most of this energy eventually converts into emission of transitions at near-infrared wavelengths. For ro-vibrational levels with <span>(v geq 3)</span>, the electron-impact excitation to electronic states followed by downward radiative transitions to the ground electronic state is the dominant mechanism of excitation. The yields for excitation to vibrational states via radiative cascading from excited electronic states are found to be <span>(1.5-2)</span> times higher than were obtained in previous studies.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 6","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323608","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

Closed-form representations of extended astrophysical thermonuclear functions 扩展天体物理热核函数的封闭形式表示

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-06-25 DOI: 10.1007/s10509-026-04600-5

Subrat Parida

引用次数: 0

Coupled transport and acceleration of suprathermal electrons by transit-time damping in corotating interaction regions 超热电子在旋转相互作用区域的耦合输运和加速度的传递时间阻尼

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-06-23 DOI: 10.1007/s10509-026-04599-9

Ji-Hoon Ha

{"title":"Coupled transport and acceleration of suprathermal electrons by transit-time damping in corotating interaction regions","authors":"Ji-Hoon Ha","doi":"10.1007/s10509-026-04599-9","DOIUrl":"10.1007/s10509-026-04599-9","url":null,"abstract":"<div><p>Particles in space and astrophysical plasmas can be efficiently accelerated through interactions with compressive magnetohydrodynamic (MHD) turbulence. In this work, we investigate the coupled transport and acceleration of suprathermal electrons in corotating interaction regions (CIRs) of the solar wind based on the transit-time damping (TTD) mechanism. Using reconstructed Parker spiral magnetic fields from solar wind observations, we estimate the transverse magnetic field gradients that characterize compressive turbulence in CIRs. From resonant interactions with fast-mode MHD waves, we derive the momentum and pitch-angle diffusion coefficients and solve the Fokker–Planck equation to follow the evolution of the electron momentum distribution. Our results show that TTD-driven stochastic acceleration naturally produces suprathermal electron populations from an initial Maxwellian distribution. The resulting suprathermal fraction can reach values of order <span>(10^{-3} - 10^{-2})</span>, depending on the plasma conditions and heliocentric distance. As the transverse magnetic field gradient decreases with radial distance, the overall acceleration efficiency is reduced while the range of resonant interactions broadens. We further find that lower plasma beta enhances the acceleration efficiency due to stronger magnetic compressions. These results suggest that compressive turbulence in CIRs can play an important role in generating suprathermal electron populations in the heliosphere.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 6","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323036","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

Testing the rigidity dependence of galactic cosmic ray intensity variations using the algorithm-selected forbush decreases 使用算法选择的灌木减小测试星系宇宙射线强度变化的刚度依赖性

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-06-16 DOI: 10.1007/s10509-026-04596-y

S. Samuneti, A. E. Chukwude, J. A. Alhassan, I. O. Eya, O. Okike

{"title":"Testing the rigidity dependence of galactic cosmic ray intensity variations using the algorithm-selected forbush decreases","authors":"S. Samuneti, A. E. Chukwude, J. A. Alhassan, I. O. Eya, O. Okike","doi":"10.1007/s10509-026-04596-y","DOIUrl":"10.1007/s10509-026-04596-y","url":null,"abstract":"<div><p>Testing the rigidity-dependent modulation of cosmic rays (CRs) through superposed epoch or quantitative regression analysis requires precise FD event timing and accurate FD magnitude of real Forbush events. However, superposition tendencies in raw CR data make analysis of CR data a non-trivial exercise. The current work demonstrates that analytical transformation of observational data, such as harmonic analysis, is required to separate the smoothed signal frequency components and other superposed spurious signals from the high-frequency component, which contains the real FD events. Given the comparative detailed and rigorous analyses performed, we speculate that some existing articles in the field, which selected FDs from raw CR data, may contain FD catalogs whose magnitude, number, and timing might possibly be biased by unwanted or spurious signals, such as 11-year solar cycle variations and CR anisotropies. For the first time, rigidity dependence modulation of CRs is tested using FD lists selected through detailed and rigorous analyses. The magnitude and timing of the FDs are not biased by spurious signals. Rather than the commonly employed two-variable regression model, we used multivariate regression analysis, taking into account contributions from other NM characteristics. We find that rigidity, altitude, latitude, and longitude make significant contributions to CR intensity variations.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 6","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148281169","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

Outstanding questions in giant planet theory 巨行星理论中悬而未决的问题

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-06-12 DOI: 10.1007/s10509-026-04595-z

Ravit Helled

引用次数: 0

The spiral pattern rotation speed of the Milky Way Galaxy in the Lin-Shu theory of small-amplitude density waves 林叔小振幅密度波理论中银河系的螺旋形旋转速度

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-06-08 DOI: 10.1007/s10509-026-04594-0

Evgeny Griv, Volodymyr Akhmetov, Asher Yahalom

{"title":"The spiral pattern rotation speed of the Milky Way Galaxy in the Lin-Shu theory of small-amplitude density waves","authors":"Evgeny Griv, Volodymyr Akhmetov, Asher Yahalom","doi":"10.1007/s10509-026-04594-0","DOIUrl":"10.1007/s10509-026-04594-0","url":null,"abstract":"<div><p>The lack of a consensus on the spiral pattern rotation speed of the Milky Way Galaxy in the Lin-Shu density wave theory frame proposed in the 1960s shows the urgency of making use of the large volume and high-quality observational data. We study the kinematics of the spiral density wave pattern in the 3 kpc solar vicinity, using main-sequence OB, A, and F stars with <i>Gaia</i> DR3. Small nonaxisymmetric perturbations of the background axially symmetric gravitational potential that generate the spiral tightly wound waves are assumed. Systematic variations of stellar velocities, induced by these perturbations, are examined numerically utilizing a nonlinear least-squares fit. A calculation leads to the pattern rotation speed of <span>(Omega _{mathrm{{p}}} = 41text{--} 49)</span> <span>(text{km},text{s}^{-1},text{kpc}^{-1})</span>. This <span>(Omega _{mathrm{{p}}})</span> differs from the angular velocity of mean circular rotation near the Sun of <span>(Omega _{0} approx 27text{ km},text{s}^{-1},text{kpc}^{-1})</span> and sets the corotation circle well inside of the solar circle, at Galactocentric distances <span>(r_{mathrm{{cor}}} = 4text{--}6)</span> kpc (for the solar distance <span>(r_{0} = 8.2)</span> kpc). In agreement with the concept of slowly growing waves, the estimated amplitude of the perturbed spiral potential is small, i.e. <span>(lesssim 7%)</span> of the background potential <span>(|Phi _{0}| sim r_{0}^{2} Omega _{0}^{2})</span>. The system’s central bar and density wave driven spirals might be dynamically coupled because the bar rotates almost with the same angular velocity, with the value of the bar rotation speed of <span>(Omega _{mathrm{{bar}}} sim 40text{ km},text{s}^{-1},text{kpc}^{-1})</span> drawn from the literature on bar dynamics.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-026-04594-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148196279","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}

引用次数: 0

Revisiting the reported period of FRB 20201124A using MCMC methods 用MCMC方法重新审视FRB 20201124A的报告周期

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-05-29 DOI: 10.1007/s10509-026-04593-1

Jun-Yi Shen, Yuan-Chuan Zou

引用次数: 0

Medusae Fossae Formation of Mars has ice-rich deposits – an independent check 火星的美杜莎凹地层有富含冰的沉积物——这是一个独立的检查

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-05-26 DOI: 10.1007/s10509-026-04590-4

Jaroslav Klokočník, Jan Kostelecký, Aleš Bezděk

{"title":"Medusae Fossae Formation of Mars has ice-rich deposits – an independent check","authors":"Jaroslav Klokočník, Jan Kostelecký, Aleš Bezděk","doi":"10.1007/s10509-026-04590-4","DOIUrl":"10.1007/s10509-026-04590-4","url":null,"abstract":"<div><p>Recent analyses of subsurface reflectors of radargrams received from the Mars Advanced Radar aboard the Mars Express orbiter (MEx) in the extensive equatorial Medusae Fossae Formation (MFF) pointed towards the presence of ice-rich and layered deposits. Our remote sensing approach working with the gravity aspects, namely with the combed strike angles, computed from the recent gravity field model of Mars (with a ground resolution of 130 km) provides an independent check. We observed clearly linearly-aligned combed strike angles for the MFF province (and for many more localities), organized into the segments with one-way common orientation of a much larger size than is the gravity model ground resolution (and in turn statistically significant). It is typical of and implies porous material, groundwater sources, subsurface water ice, light constituents in the sedimentary layers or their various mixtures. Also, for the MFF, it is indicative of a lower density or higher porosity material, compared to surrounding rocks. It is proposed that this result is evidence of presence of ice in MFF.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-026-04590-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009635","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}

引用次数: 0

Photospheric abundances of the rapidly-rotating A-type star Altair 快速旋转的a型恒星牛郎星的光球丰度

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-05-25 DOI: 10.1007/s10509-026-04592-2

Yoichi Takeda

{"title":"Photospheric abundances of the rapidly-rotating A-type star Altair","authors":"Yoichi Takeda","doi":"10.1007/s10509-026-04592-2","DOIUrl":"10.1007/s10509-026-04592-2","url":null,"abstract":"<div><p>Altair is an A-type star known to have an appreciably oblate shape owing to its very fast rotation (<span>(sim 300)</span> km s<sup>−1</sup>). Despite of numerous publications on this star, its chemical abundances have been scarcely investigated so far, presumably because of the practical difficulty that spectral lines are considerably broadened by rapid rotation and badly blended with each other. Motivated by this situation, a spectroscopic analysis was conducted to study the photospheric abundances of Altair by using the synthetic spectrum-fitting technique, in order to clarify whether or not any chemical peculiarities exist. The microturbulent velocity was determined to be 2.9 (<span>(pm 0.9)</span>) km s<sup>−1</sup> by requiring that the metallicity does not show any systematic region-dependence. Then, the abundances of 17 elements (C, N, O, Mg, Al, Si, S, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Zn, Sr, Ba) were derived, where the non-LTE effect was taken into consideration as much as possible. The results revealed considerable region-by-region dispersion (several tenths dex or even more), reflecting the difficulty of reliable abundance determination for such a very rapid rotator. Nevertheless, the differential mean abundances relative to the Sun turned out to fall within <span>(-0.5 lesssim )</span> [X/H] <span>(lesssim +0.3)</span> for all elements without any dependence upon the atomic number. Accordingly, we may conclude that (1) no appreciable anomalies of chemical abundance patterns exist in the atmosphere of Altair, (2) but its global metallicity is likely to be slightly subsolar (<span>(sim -0.2)</span> dex on the average).</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009868","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

Effect of radiation pressure, nonsynchronous rotation, and eccentric orbits on the Lagrangian points and Roche potential in close binary system of stars 辐射压力、非同步旋转和偏心轨道对紧密双星系统拉格朗日点和罗氏势的影响

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-05-25 DOI: 10.1007/s10509-026-04587-z

Bulbul Hooda, Ankush Pathania, Arvind Kumar Lal

{"title":"Effect of radiation pressure, nonsynchronous rotation, and eccentric orbits on the Lagrangian points and Roche potential in close binary system of stars","authors":"Bulbul Hooda, Ankush Pathania, Arvind Kumar Lal","doi":"10.1007/s10509-026-04587-z","DOIUrl":"10.1007/s10509-026-04587-z","url":null,"abstract":"<div><p>The Roche potential plays a pivotal role in studying the problems of rotating stars and stars in the close binary systems. The standard or classical expression of Roche potential considers the effects of gravitational and centrifugal forces and excludes the effect due to various other forces. However, certain authors have modified the standard expression of Roche potential by including the effects of radiation pressure, nonsynchronous rotation, eccentricity of the orbits, non-uniform rotation and misaligned axis of rotation and revolution. In these studies, the modification have been incorporated in the expression of standard Roche potential by considering either one or at most two effects. In this paper we have obtained a more generalized expression of Roche potential that considers more than two effects, including the radiation pressure, nonsynchronous rotation and eccentricity of the orbits. This expression has been then used to determine the effect of radiation pressure, nonsynchronous rotation, and eccentricity on the position of the colinear Lagrangian points, and corresponding Roche potential in close binary system of stars, The result of the present study shows that when the effects of radiation pressure, nonsynchronous rotation and eccentricity are considered then there is an appreciable change in the position of colinear Lagrangian points and corresponding Roche potential of the stars in close binary systems.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009619","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