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Model of Charged Anisotropic Strange Stars in Minimally Coupled f R Gravity 最小耦合重力下带电各向异性奇异星模型
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2021-01-02 DOI: 10.1155/2021/6698208
H. Nazar, G. Abbas
<jats:p>In the present article, we have investigated a new family of nonsingular solutions of static relativistic compact sphere which incorporates the characteristics of anisotropic fluid and electromagnetic field in the context of minimally coupled <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M2"> <mi>f</mi> <mfenced open="(" close=")" separators="|"> <mrow> <mi>R</mi> </mrow> </mfenced> </math> </jats:inline-formula> theory of gravity. The strange matter <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3"> <mtext>MIT</mtext> </math> </jats:inline-formula> bag model equation of state (EoS) has been considered along with the usual forms of the Karori–Barua <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4"> <mfenced open="(" close=")" separators="|"> <mrow> <mtext>KB</mtext> </mrow> </mfenced> </math> </jats:inline-formula> metric potentials. For this purpose, we derived the Einstein–Maxwell field equations in the assistance of strange matter EoS and <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M5"> <mtext>KB</mtext> </math> </jats:inline-formula> type ansatz by employing the two viable and cosmologically well-consistent models of <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M6"> <mi>f</mi> <mfenced open="(" close=")" separators="|"> <mrow> <mi>R</mi> </mrow> </mfenced> <mo>=</mo> <mi>R</mi> <mo>+</mo> <mi>γ</mi> <msup> <mrow> <mi>R</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </math> </jats:inline-formula> and <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M7"> <mi>f</mi> <mfenced open="(" close=")" separators="|"> <mrow> <mi>R</mi> </mrow>
56  km,和CS3 4U1820−30x~=10  km,如表1-6所示。最后,我们注意到,在两个著名的fR模型的背景下,我们提出的带电致密恒星物体符合稳定平衡位置的所有必要条件它也非常适合组成奇异的夸克星物体。
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引用次数: 3
Motion of the Infinitesimal Variable Mass in the Generalized Circular Restricted Three-Body Problem under the Effect of Asteroids Belt 广义圆形受限三体问题中无穷小变质量在小行星带作用下的运动
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-12-18 DOI: 10.1155/2020/6684728
F. Bouaziz-Kellil
The present paper deals with the study of the motion’s properties of the infinitesimal variable mass body moving in the same orbital plan as two massive bodies (considered as primaries). It is assumed that the massive bodies have radiating effects, have oblate shapes, and are moving in circular orbits around their common center of mass. Using the procedures established by Singh and Abouelmagd, we determined the equations of motion of the infinitesimal body for which we assumed that under the effects of radiation and oblateness of the primaries, its mass varies following Jean’s law. We evaluated analytically and numerically the locations of equilibrium points and examined the stability of these equilibrium points. Finally, we found that all the points are unstable.
本文研究了在同一轨道平面上与两个大质量物体(被认为是主质量物体)运动的无穷小变质量物体的运动性质。假设大质量物体具有辐射效应,呈扁球形,并围绕其共同质心在圆形轨道上运动。使用Singh和Abouelmagd建立的程序,我们确定了无穷小物体的运动方程,我们假设在辐射和初级物体的扁率的影响下,它的质量根据吉恩定律而变化。我们对平衡点的位置进行了分析和数值评估,并检查了这些平衡点的稳定性。最后,我们发现所有的点都是不稳定的。
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引用次数: 6
Evolution of Periodic Orbits within the Frame of Formation Satellites 编队卫星框架内周期轨道的演化
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-12-18 DOI: 10.1155/2020/1348319
Elbaz I. Abouelmagd, Mitali J. Doshi, Niraj M. Pathak
In the framework of formation satellites, the periodic orbits of deputy satellite are analyzed when the chief satellite is moving in an elliptical orbit. This analysis is developed on 1- to 10-loop periodic orbits of the deputy satellite. These orbits along with their associated loops are discussed under some specific initial position sets. The effects of different initial velocities, initial true anomalies, and eccentricities on the initial position and orbital period of periodic orbits of deputy satellite are investigated.
在编队卫星的框架下,分析了主卫星在椭圆轨道上运动时副卫星的周期轨道。该分析是在副卫星的1至10圈周期轨道上进行的。这些轨道及其相关的环在一些特定的初始位置集下进行了讨论。研究了不同初始速度、初始真异常和偏心度对副卫星周期轨道初始位置和轨道周期的影响。
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引用次数: 2
Quartic Integral in Rigid Body-Gyrostat Dynamics 刚体-陀螺动力学中的四次积分
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-12-11 DOI: 10.1155/2020/6651277
C. Mnasri, A. Elmandouh
In this work, we investigate the problem of constructing new integrable problems in the dynamics of the rigid body rotating about its fixed point as results of the effect of a combination of potential and gyroscopic forces possessing a common symmetry axis. We introduce two new integrable problems in a rigid body dynamics that generalize some integrable problems in this field, known by names of Chaplygin and Yehia–Elmandouh.
在这项工作中,我们研究了在具有共同对称轴的势力和陀螺力的组合作用下,围绕固定点旋转的刚体动力学中构造新的可积问题的问题。我们引入了刚体动力学中的两个新的可积问题,它们推广了该领域的一些可积问题,这些问题被称为Chaplygin和Yehia-Elmandouh。
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引用次数: 0
New Treatment of the Rotary Motion of a Rigid Body with Estimated Natural Frequency 用估计固有频率处理刚体旋转运动的新方法
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-12-03 DOI: 10.1155/2020/6629183
A. I. Ismail
In this paper, the problem of the motion of a rigid body about a fixed point under the action of a Newtonian force field is studied when the natural frequency . This case of singularity appears in the previous works and deals with different bodies which are classified according to the moments of inertia. Using the large parameter method, the periodic solutions for the equations of motion of this problem are obtained in terms of a large parameter, which will be defined later. The geometric interpretation of the considered motion will be given in terms of Euler’s angles. The numerical solutions for the system of equations of motion are obtained by one of the well-known numerical methods. The comparison between the obtained numerical solutions and analytical ones is carried out to show the errors between them and to prove the accuracy of both used techniques. In the end, we obtain the case of the regular precession type as a special case. The stability of the motion is considered by the phase diagram procedures.
本文研究了在牛顿力场作用下,当固有频率为零时,刚体绕不动点的运动问题。这种奇异性的情况出现在以前的工作中,并处理根据惯性矩分类的不同物体。使用大参数方法,以大参数的形式获得了该问题运动方程的周期解,稍后将对其进行定义。所考虑的运动的几何解释将根据欧拉角给出。运动方程组的数值解是通过一种众所周知的数值方法获得的。将所获得的数值解与解析解进行比较,以显示它们之间的误差,并证明两种所用技术的准确性。最后,我们得到了正则进动型的一个特例。相图程序考虑了运动的稳定性。
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引用次数: 0
Light Speed Invariant Solution and Its Enlightenment of Field Equation of General Relativity 广义相对论场方程的光速不变量解及其启示
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-11-29 DOI: 10.1155/2020/3930947
J. Yang
A systematic examination of the basic theory of general relativity is made, the meaning of coordinates again is emphasized, the confusion caused by unclear meaning of coordinates in the past is corrected, and the expression of the theory is made more accurate. Firstly, the equation of Einstein’s gravitational field is solved in the usual coordinate system, the existence of light speed invariant solution in the spherically symmetric gravitational field is proved, and in the same time, the solution is determined. It turns out that black holes are not an inevitable prediction of general relativity. +e more exact formulas for calculating the curvature of light on the surface of the Sun and the precession angle of the orbit of Mercury are given, and the convergence of general relativistic gravity and special relativistic mechanics under the weak field approximation is realized. Finally, it is shown that the coupling coefficient of the gravitational field equation is not unique. Modifying this coefficient is an ideal project to eliminate the singularities of general relativity on the condition keeping the field equation concise and elegant, and moreover, it reveals that dark matter and dark energy are the negative energy field in the matter, the expansion of the universe is the appearance of the gradual formation of galaxies in accordance with fractal rules, not only the space between galaxies is expanding but also the galaxies themselves are also expanding, new matter is continuously generated in the celestial bodies, for the first time, the unity of fractal geometry and cosmic dynamics of general relativity is realized, and the formation and evolution of galaxies are brought into the fractal generation mode. +is is a living and vivacious universe in which all aspects are gradually strengthening, in sharp contrast to the dying universe under the current cosmological framework.
对广义相对论的基本理论作了系统的考察,重新强调了坐标的意义,纠正了过去由于坐标意义不清而引起的混乱,使理论的表达更加准确。首先在常用坐标系下求解爱因斯坦引力场方程,证明了球对称引力场中光速不变量解的存在性,同时确定了其解。事实证明,黑洞并不是广义相对论的必然预言。给出了太阳表面光曲率和水星轨道进动角的更精确计算公式,实现了广义相对论引力和狭义相对论力学在弱场近似下的收敛。最后证明了引力场方程的耦合系数不是唯一的。修正该系数是在保持场方程简洁优雅的条件下消除广义相对论奇点的理想方案,并且揭示了暗物质和暗能量是物质中的负能量场,宇宙的膨胀是星系按照分形规律逐渐形成的表象,不仅星系之间的空间在膨胀,而且星系本身也在膨胀。天体中不断产生新物质,首次实现了广义相对论的分形几何与宇宙动力学的统一,将星系的形成演化带入分形生成模式。它是一个有生命的、活泼的宇宙,其中的各个方面都在逐渐加强,与目前宇宙学框架下垂死的宇宙形成鲜明对比。
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引用次数: 1
Conformable Fractional Models of the Stellar Helium Burning via Artificial Neural Networks 基于人工神经网络的恒星氦燃烧保形分数模型
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-11-23 DOI: 10.22541/au.160616166.67887623/v1
E. Abdel-salam, M. Nouh, Y. A. Azzam, M. Jazmati
The helium burning phase represents the second stage that the star used to consume nuclear fuel in its interior. In this stage, the three elements, carbon, oxygen, and neon, are synthesized. The present paper is twofold: firstly, it develops an analytical solution to the system of the conformable fractional differential equations of the helium burning network, where we used, for this purpose, the series expansion method and obtained recurrence relations for the product abundances, that is, helium, carbon, oxygen, and neon. Using four different initial abundances, we calculated 44 gas models covering the range of the fractional parameterα=0.5−1with stepΔα=0.05. We found that the effects of the fractional parameter on the product abundances are small which coincides with the results obtained by a previous study. Secondly, we introduced the mathematical model of the neural network (NN) and developed a neural network algorithm to simulate the helium burning network using a feed-forward process. A comparison between the NN and the analytical models revealed very good agreement for all gas models. We found that NN could be considered as a powerful tool to solve and model nuclear burning networks and could be applied to the other nuclear stellar burning networks.
氦燃烧阶段代表了恒星内部消耗核燃料的第二阶段。在这个阶段,碳、氧和氖这三种元素被合成。本文有两个方面:首先,对氦燃烧网络的保形分数阶微分方程组进行了解析解,为此,我们使用级数展开法,得到了氦、碳、氧和氖的乘积丰度的递推关系。使用四种不同的初始丰度,我们计算了44个气体模型,覆盖了分数参数α=0.5−1的范围,步长Δα=0.05。我们发现分数参数对产物丰度的影响很小,这与之前的研究结果一致。其次,我们介绍了神经网络的数学模型,并开发了一种使用前馈过程模拟氦气燃烧网络的神经网络算法。神经网络和分析模型之间的比较表明,所有气体模型都非常一致。我们发现,神经网络可以被认为是求解和建模核燃烧网络的强大工具,并可以应用于其他核恒星燃烧网络。
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引用次数: 3
Wormhole Models and Energy Conditions in f ℛ Gravity with the Hu–Sawicki Model 基于Hu-Sawicki模型的引力虫洞模型和能量条件
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-11-22 DOI: 10.1155/2020/8813611
Ouziala Ikram, G. Mustafa
In this recent study, we shall investigate the wormhole models with a Hu–Sawicki model in the framework of gravity. Spherically static symmetric space-time is considered to construct wormhole models with the anisotropic fluid distribution. The traceless matter is discussed by imposing a particular equation of state. To address the important conditions of the shape function of the wormhole geometry, we have used the particular values of the involved parameters. Furthermore, different energy conditions are discussed to check the nature of matter against two specific models. The null energy condition is observed to be violated for both of the models. It is mentioned that our inquired results are acceptable.
在最近的研究中,我们将在重力的框架下用Hu-Sawicki模型来研究虫洞模型。考虑球静力对称时空构造具有各向异性流体分布的虫洞模型。通过施加一个特定的状态方程来讨论无迹物质。为了解决虫洞几何形状函数的重要条件,我们使用了相关参数的特定值。此外,还讨论了不同的能量条件,以根据两种特定的模型来检验物质的性质。观察到两种模型都不符合零能条件。它提到我们的询价结果是可以接受的。
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引用次数: 2
Isotropic Gravastar Model in Rastall Gravity Rastall重力中的各向同性Gravastar模型
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-11-16 DOI: 10.1155/2020/8861168
G. Abbas, K. Majeed
In the present paper, we have introduced a new model of gravastar with an isotropic matter distribution in Rastall gravity by the Mazur–Mottola (2004) mechanism. Mazur–Mottola approach is about the construction of gravastar which is predicted as an alternative to black hole. By following this convention, we define gravastar in the form of three phases. The first one is an interior phase which has negative density; the second part consists of thin shell comprising ultrarelativistic stiff fluid for which we have discussed the length, energy, and entropy. By the graphical analysis of entropy, we have shown that our proposed thin shell gravastar model is potentially stable. The third phase of gravastar is defined by the exterior Schwarzschild geometry. For the interior of gravastar, we have found the analytical solutions free from any singularity and the event horizon in the framework of Rastall gravity.
在本文中,我们通过Mazur–Mottola(2004)机制介绍了一种在Rastall重力中具有各向同性物质分布的gravastar新模型。Mazur–Mottola方法是关于建造gravastar,它被预测为黑洞的替代方案。通过遵循这个惯例,我们将gravastar定义为三个阶段。第一种是具有负密度的内相;第二部分是由超相对论刚性流体组成的薄壳层,我们讨论了其长度、能量和熵。通过熵的图解分析,我们已经表明我们提出的薄壳gravastar模型是潜在的稳定。gravastar的第三阶段是由外部Schwarzschild几何定义的。对于gravastar内部,我们在Rastall引力框架下找到了不存在任何奇异性和事件视界的解析解。
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引用次数: 8
Approximate Analytical Three-Dimensional Multiple Time Scales Solution to a Circular Restricted Three-Body Problem 圆形受限三体问题的三维多时间尺度近似解析解
IF 1.4 4区 物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2020-11-10 DOI: 10.1155/2020/8868137
F. Gao, Yongqing Wang
We illustrate the chaotic nature of the circular restricted three-body problem from the perspective of the bifurcation diagram with respect to the mass ratio parameter. Moreover, it is shown that when the frequency ratio in different directions of the classical problem is irrational, it has the quasiperiodic characteristics. In addition, a three-dimensional approximate solution to this problem under two time scales is proposed by using the multiple time scales method.
我们从质量比参数的分岔图的角度说明了圆形受限三体问题的混沌性质。此外,当经典问题在不同方向上的频率比不合理时,它具有准周期特性。在此基础上,利用多时间尺度法给出了该问题在两个时间尺度下的三维近似解。
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引用次数: 2
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