共查询到20条相似文献，搜索用时 46 毫秒
1.
Walter Petry 《Astrophysics and Space Science》1995,232(2):233-240
The previously studied 2-post-Newtonian approximation of the gravitational field of a nonstationary spherically symmetric star in flat space-time theory of gravitation is applied to the motion of a test particle in the orbit of the star. The orbit is different from the one of Einstein's general theory of relativity. A general formula for the deviation of the orbit from a circle is given. In the special case of a radially oscillating star, being homogeneous to Newtonian accuracy, the orbit of the test particle also oscillates radially with small amplitude about a fixed orbit (circle). 相似文献
2.
Walter Petry 《Astrophysics and Space Science》1994,211(1):71-91
Starting from a previously studied theory of gravitation in flat space-time the post-Newtonian approximation of the gravitational field of an nonstationary spherically symmetric star is derived. To the post-Newtonian order the equations of motion and the conserved total energy of a collapsing star are given. Birkhoff's theorem holds to this accuracy. 相似文献
3.
B. C. Tewari 《Astrophysics and Space Science》2006,306(4):273-277
New Solution of Einstein’s equations for spherically symmetric radiating fluid distribution has been presented. The solution
is used to construct a model of radiating star. The interior space-time metric is matched with Vaidya exterior metric at zero
pressure boundary. 相似文献
4.
In this paper, we investigate spherically symmetric perfect fluid gravitational collapse in metric f(R) gravity. We take non-static spherically symmetric metric in the interior region and static spherically symmetric metric
in the exterior region of a star. The junction conditions between interior and exterior spacetimes are derived. The field
equations in f(R) theory are solved using the assumption of constant Ricci scalar. Inserting their solution into junction conditions, the
gravitational mass is found. Further, the apparent horizons and their time of formation is discussed. We conclude that the
constant scalar curvature term f(R
0) acts as a source of repulsive force and thus slows down the collapse of matter. The comparison with the corresponding results
available in general relativity indicates that f(R
0) plays the role of the cosmological constant. 相似文献
5.
6.
M. K. Mak T. Harko Department of Physics The Hong Kong University of Science Technology Clear Water Bay Hong Kong Department of Physics The University of Hong Kong Pokfulam Hong Kong 《中国天文和天体物理学报》2002,2(3):248-259
We present an exact analytical solution of the gravitational field equations describing a static spherically symmetric anisotropic quark matter distribution. The radial pressure inside the star is assumed to obey a linear equation of state, while the tangential pressure is a complicated function of the radial coordinate. In order to obtain the general solution of the field equations a particular density profile inside the star is also assumed. The anisotropic pressure distribution leads to an increase in the maximum radius and mass of the quark star, which in the present model is around three solar masses. 相似文献
7.
R. M. Avakian E. V. Chubarian A. V. Sarkissian E. Schmutzer 《Astronomische Nachrichten》1990,311(6):343-350
In order to confront the Projective Unified Field Theory with physical experience it is appropriate to apply this theory also to astrophysical objects, for mathematical reasons in particular to a static spherically symmetric matter distribution as a rough model for a star (e.g. neutron star or another exotic compact object). The problem mentioned is treated here as far as possible analytically in order to prepare the basis for the numerical approach. 相似文献
8.
The integration of the Einstein-Maxwell equations for a spherically symmetric distribution of collapsing charged matter, is accomplished. Comparison with a neutral corresponding solution allows us to analyse the effect of electric charge on the evolution of the sphere. The solution is matched across the boundary of the distribution to the exterior radiating Vaydia-Reissner-Nordstrom spacetime. It is shown that the presence of the electric charge delays the contraction of the sphere. 相似文献
9.
A. I. Tsygan 《Astrophysics and Space Science》1984,103(1):199-200
The spherically symmetric accretion of matter onto a neutron star with a weak magnetic field is shown to be accompanied by the generation of gamma rays due to the Comptonization of X=rays from the neutron star on the flow of incident plasma. 相似文献
10.
V. S. Imshennik K. V. Manukovskii D. K. Nadyozhin M. S. Popov 《Astronomy Letters》2002,28(12):821-834
We analyze the behavior of the outer envelope in a massive star during and after the collapse of its iron core into a protoneutron star (PNS) in terms of the equations of one-dimensional spherically symmetric ideal hydrodynamics. The profiles obtained in the studies of the evolution of massive stars up to the final stages of their existence, immediately before a supernova explosion (Boyes et al. 1999), are used as the initial data for the distribution of thermodynamic quantities in the envelope. We use a complex equation of state for matter with allowances made for arbitrary electron degeneracy and relativity, the appearance of electron-positron pairs, the presence of radiation, and the possibility of iron nuclei dissociating into free nucleons and helium nuclei. We performed calculations with the help of a numerical scheme based on Godunov's method. These calculations allowed us to ascertain whether the emersion of the outer envelope in a massive star is possible through the following two mechanisms: first, the decrease in the gravitational mass of the central PNS through neutrino-signal emission and, second, the effect of hot nucleon bubbles, which are most likely formed in the PNS corona, on the envelope emersion. We show that the second mechanism is highly efficient in the range of acceptable masses of the nucleon bubbles (≤0.01M ⊙) simulated in our hydrodynamic calculations in a rough, spherically symmetric approximation. 相似文献
11.
Assuming that the physical 3-spacet = const in a superdense star is spheroidal, a static spherically symmetric model based on an exact solution of Einstein’s
equations is given which will permit densities of the order of 2 × 1014 gm cm-3, radii of the order of a few kilometers and masses up to about four times the solar mass. 相似文献
12.
Dany Vanbeveren 《Astrophysics and Space Science》1978,57(1):41-51
Using a spherically symmetric approximation for the radiation pressure force to compute a possible critical surface for binary systems, previous authors found that the surface opens up at the far side of the companion. It is shown that this effect may be unreal, and could be a consequence of the simple approximation for the radiation pressure force. Due to the influence of the radiation force, mass will be lost over the whole surface of the star. In that way much mass could leave the system in massive binary systems. On the basis of evolutionary models, including mass loss by stellar wind, our results were applied on the X-ray binaries 3U 1700-37 and HD 77581. 相似文献
13.
A relativistic, first-order differential equation is derived for the accumulated moment of inertia of a spherically symmetric
celestial body. An approximate equation is proposed to describe the contribution of relativistic effects to the moment of
inertia of a superdense star. For configurations of an incompressible fluid, this approximation describes the results of the
numerical calculations of Chandrasekhar and Miller to within 5% in the entire range of central pressures from 0 to ∞.
Translated from Astrofizika, Vol. 40, No. 1, pp. 87–96, January–March, 1997. 相似文献
14.
We construct an idealized spherically symmetric relativistic model of an exploding object within the framework of the theory of surface layers in GR. A Vaidya solution for a radially radiating star is matched through a spherical shell of dust to a Schwarzschild solution. The (incomplete) equations for the motion of the spherical shell of dust and the radiation density of the Vaidya solution, as given by the matching conditions, are reduced to a first-order system and a general analysis of the characteristics of the motion is given. This system of differential equations is completed, adding a relation between the unknowns which represents the simplest way to avoid an unphysical singularity in the motion. The results of a numerical integration of the equations are presented in two cases which we think may have some relationship to stellar explosions. A comparative set of results for other solutions is also given, and some possible generalizations of the model are pointed out. 相似文献
15.
W. Petry 《Astrophysics and Space Science》2000,272(4):353-368
The 1-post-Newtonian approximation of perfect fluid in cosmological models of the theory of gravitation in flat space-time
is studied. The equations of motion are given in evolution form. At high redshifts the terms of post-Newtonian approximation
are important in studying the development of inhomogeneities on scales smaller than galaxies but at present time these terms
only take effect on very large scales.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
The linear adiabatic oscillations of a spherically symmetric star are analyzed in terms of potential fields. It is found that
all displacement fields ϱξ can be described as either spheroidal or toroidal fields. 相似文献
17.
Babur M. Mirza 《Monthly notices of the Royal Astronomical Society》2009,395(4):2288-2291
The isothermal Lane–Emden equation arises in many astrophysical problems, in particular in modelling of a self-gravitating, polytropic gas in a spherically symmetric configuration. In this work, the isothermal Lane–Emden equation is investigated using the fractional approximation technique. The method provides an efficient and accurate way of obtaining approximate analytic solution to the Lane–Emden equation thus is useful in the modelling of self-gravitating gaseous spheres in astrophysics. 相似文献
18.
An approximate solution has been obtained for the problem of multiple scattering of light in an optically thin, inhomogeneous spherically symmetric planetary atmosphere illuminated by parallel solar radiation. A three-stream division of the radiation field has been made and a generalized Eddington approximation developed to solve the moment equations of the problem. 相似文献
19.
We report a general solution in one of the gravitational potentials to the Einstein system in static spherically symmetric spacetime, modeling anisotropic strange quark matter by imposing a linear barotropic equation of state. The model generated by choosing Tolmann IV form for the gravitational potential is shown to contain the previously known anisotropic dark energy star model of Lobo (Class. Quantum Gravity 23:1525, 2006) and isotropic models of de Sitter and Einstein. Moreover, the model is shown to be physically admissible and corroborate with experimental observations on strange star candidates such as SAX J1808.4-3658 and 4U 1820-30. 相似文献
20.
We have obtained static and spherically symmetric self-gravitating solution of the field equations for anisotropic distribution of matter in higher- dimensional in the context of Einstein’s general theory of relativity. This work is an extension of the previous work of Hector Rago (Astrophys. Space Sci. 183:333, 1991) for four dimensional space-time. The solutions are matched to the analytical solutions for spherically symmetric self gravitating distribution of anisotropic matter obtained by Hector Rago (1991) for n=2. 相似文献