Astrophysics最新文献_第5页

Methanimine in Cool Cosmic Objects Using Accurate Collisional Rate Coefficients 利用精确的碰撞率系数研究冷宇宙天体中的甲烷化物

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-10-14 DOI: 10.1007/s10511-024-09838-x

S. Chandra, M. K. Sharma

{"title":"Methanimine in Cool Cosmic Objects Using Accurate Collisional Rate Coefficients","authors":"S. Chandra, M. K. Sharma","doi":"10.1007/s10511-024-09838-x","DOIUrl":"10.1007/s10511-024-09838-x","url":null,"abstract":"Accurate collisional rate coefficients for collisional transitions between 15 rotational levels of methanimine, colliding with p-H2 molecule, are available. Methanimine is a planar, asymmetric top molecule having electric dipole moment with components μa = 1.3396 Debye and μb = 1.4461 Debye, and thus, producing both the a and b type spectral lines of nearly equal intensities. Therefore, all the rotational levels need to be considered together. Between 15 rotational levels, 105 collisional transitions are considered in an investigation by others. We have discussed that each level is not connected with all others through the collisions, and therefore, there should be 77 instead of 105 collisional transitions between 15 levels of methanimine. With availability of accurate collisional rate coefficients, it is worth to perform the Sobolev analysis of methanimine. We have found six weak MASER transitions, 110-111, 211-212, 312-313, 41.3-41.4, 303-212 and 40.4-31.3, and one transition 111-202, showing anomalous absorption. These seven lines may play important role for the methanimine.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 3","pages":"364 - 374"},"PeriodicalIF":0.6,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443245","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

Thermodiffusion Unipolar Electric Generator 热扩散单极发电机

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-10-14 DOI: 10.1007/s10511-024-09841-2

G. S. Bisnovatyi-Kogan, M. V. Glushikhina

引用次数: 0

BSN: First Photometric Light Curve Analysis of Two W-Type Contact Binary Systems OP Boo and V0511 Cam BSN：对 OP Boo 和 V0511 Cam 两种 W 型接触式二进制系统的首次光度光曲线分析

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-10-11 DOI: 10.1007/s10511-024-09834-1

A. Poro, M. Tanriver, A. Keskin, A. Bulut, S. Rabieefar, M. M. Gharghabi, F. Walter, S. Holy

{"title":"BSN: First Photometric Light Curve Analysis of Two W-Type Contact Binary Systems OP Boo and V0511 Cam","authors":"A. Poro, M. Tanriver, A. Keskin, A. Bulut, S. Rabieefar, M. M. Gharghabi, F. Walter, S. Holy","doi":"10.1007/s10511-024-09834-1","DOIUrl":"10.1007/s10511-024-09834-1","url":null,"abstract":"This study presented the first light curve analysis of the OP Boo and V0511 Cam binary stars, which was conducted in the frame of the Binary Systems of South and North (BSN) Project. Photometric ground-based observations were conducted with standard filters at two observatories in the Czech Republic. We computed a new ephemeris for each of the systems using our extracted times of minima, TESS data, and additional literature. Linear fits for O-C diagrams of both systems were considered using the Markov Chain Monte Carlo (MCMC) method. The light curves were analyzed using the Wilson-Devinney (WD) binary code combined with the Monte Carlo (MC) simulation. The light curve solutions of both target systems required a cold starspot. The absolute parameters of the systems were calculated by using a P – M parameter relationship. The positions of the systems were also depicted on the Hertzsprung-Russell (HR), P - L, logMtot - logJ0, and T - M diagrams. The hotter component in both systems is determined to be a more massive star. Therefore, it can be concluded that both systems are W-type contact binary systems.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 3","pages":"299 - 315"},"PeriodicalIF":0.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443240","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

Large Diffuse Dwarfs in the Dynamically Cold Triple Galaxy Systems 动态冷三重星系系统中的大型漫射矮星

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-10-11 DOI: 10.1007/s10511-024-09832-3

I. D. Karachentsev, A. E. Nazarova, V. E. Karachentseva

引用次数: 0

Probing Pseudoscalars with Pulsar Polarisation Data Sets 利用脉冲星极化数据集探测伪恒星

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-10-11 DOI: 10.1007/s10511-024-09833-2

K. Chand, S. Mandal

引用次数: 0

Reanalyzing the Light Curves and Absolute Parameters of Twenty Contact Binary Stars Using Tess Data 利用泰斯数据重新分析 20 颗接触双星的光变曲线和绝对参数

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-10-11 DOI: 10.1007/s10511-024-09835-0

E. Paki, A. Poro

{"title":"Reanalyzing the Light Curves and Absolute Parameters of Twenty Contact Binary Stars Using Tess Data","authors":"E. Paki, A. Poro","doi":"10.1007/s10511-024-09835-0","DOIUrl":"10.1007/s10511-024-09835-0","url":null,"abstract":"Reanalyzing contact binaries with space-based photometric data and investigating possible parameter changes can yield accurate samples for theoretical studies. We investigated light curve solutions and fundamental parameters for twenty contact binary systems. The most recent Transiting Exoplanet Survey Satellite (TESS) data is used to analyze. The target systems in the investigation have an orbital period of less than 0.58 days. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs (PHOEBE) Python code version 2.4.9. The results show that systems had various mass ratios from q = 0.149 to q = 3.915, fillout factors (the degree of contact) from f = 0.072 to f = 0.566, and inclinations from i = 52°.8 to i = 87°.3. The effective temperature of the stars was less than 7016 K, which was expected given the features of most contact binary stars. Twelve of the target systems' light curves were asymmetrical in the maxima, showing the O'Connell effect, and a starspot was required for light curve solutions. The estimation of the absolute parameters of the binary systems was presented using the a - P empirical relationship and discussed. The orbital angular momentum J0 of the systems was calculated. The positions of the systems were also depicted on the M - L, M - R, q - Lratio, Mtot - J0, and T - M diagrams.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 3","pages":"316 - 329"},"PeriodicalIF":0.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443237","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

A Simple Analytical Method Using Fokker-Planck Equation for Modeling Particle Acceleration At Astrophysical Shocks 使用福克-普朗克方程模拟天体物理冲击下粒子加速度的简单分析方法

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-10-11 DOI: 10.1007/s10511-024-09836-z

J.-H. Ha

{"title":"A Simple Analytical Method Using Fokker-Planck Equation for Modeling Particle Acceleration At Astrophysical Shocks","authors":"J.-H. Ha","doi":"10.1007/s10511-024-09836-z","DOIUrl":"10.1007/s10511-024-09836-z","url":null,"abstract":"Shocks are ubiquitous in astrophysical environments, and particle acceleration at such astrophysical shocks is related to high-energy phenomena. In particular, the acceleration mechanism and the time evolution of the particle distribution function have been extensively examined. This paper describes a simple analytic method using the one-dimensional Fokker-Planck equation in the test-particle regime. We aim to investigate the evolution of the particle distribution function in the shock upstream, which could be streaming toward Earth along the open magnetic field geometry. The behavior of the analytical solution is examined over a wide range of parameters representing shock structure, such as the shock Mach number, plasma beta, injection fraction into diffusive shock acceleration, and the scale of the upstream magnetic field. The behavior is associated with upstream turbulence for diffusive shock acceleration, as expected. Additionally, pre-accelerated particles could affect the time evolution of the particle distribution only when the radiative or advection losses are small enough for the pre-accelerated distribution to have a flatter power-law slope than the power-law slope based on shock acceleration theory. We also provide a formula for a spherically expanding shock and its relevant application to calculate high-energy emission due to hadronic interactions. We suggest that the simple analytic method could be applied to examine astrophysical shocks with a wide range of plasma parameters.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 3","pages":"330 - 347"},"PeriodicalIF":0.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443239","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

Fermionic Vacuum Stresses in Models with Toroidal Compact Dimensions 环状紧凑尺寸模型中的费米子真空应力

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-08-03 DOI: 10.1007/s10511-024-09830-5

A. A. Saharian, R. M. Avagyan, G. H. Harutyuynyan, G. H. Nikoghosyan

引用次数: 0

Viscous Plane Symmetric String Cosmological Model in f (R) Gravity f（R）引力下的粘性平面对称弦宇宙学模型

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-07-31 DOI: 10.1007/s10511-024-09826-1

A. Dabre, Pallavi Makode

引用次数: 0

Re-Examining Berman’s Parametrization of the Hubble Parameter in the Context of Late-Time Acceleration 在晚时间加速度的背景下重新审视伯尔曼的哈勃参数参数化

IF 0.6 4区物理与天体物理

Astrophysics Pub Date : 2024-07-31 DOI: 10.1007/s10511-024-09831-4

K. R. Mishra, R. Kumar, S. K. J. Pacif

{"title":"Re-Examining Berman’s Parametrization of the Hubble Parameter in the Context of Late-Time Acceleration","authors":"K. R. Mishra, R. Kumar, S. K. J. Pacif","doi":"10.1007/s10511-024-09831-4","DOIUrl":"10.1007/s10511-024-09831-4","url":null,"abstract":"In this paper, we have revisited the Berman’s idea of the variation of Hubble parameter. While previously explored in the context of Λ-varying cosmologies, where scale factor variations yield linear universe expansion, this parametrization has undergone extensive scrutiny. Our investigation, however, explores into its implications in the context of late-time cosmic acceleration, within the framework of classical general relativity, adopting the Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime as our background metric. Our analysis offers a precise solution to Einstein’s field equations (EFEs) in a model-independent way, affording a thorough assessment of both geometrical and physical model parameters. Additionally, this study supplements its findings with graphical representations of the evolving cosmological parameters across flat, closed, and open universe scenarios, all subject to constraints derived from the model parameters. In synthesizing these results, we shed light on the intricate interplay between cosmic acceleration, dark energy, and the parametrization of the Hubble parameter, thereby providing valuable insights into the fundamental mechanics of our universe.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 2","pages":"246 - 265"},"PeriodicalIF":0.6,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141869724","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