scholarly journals NONADIABATIC SPHERICAL COLLAPSE WITH A TWO-FLUID ATMOSPHERE

2013 ◽  
Vol 22 (07) ◽  
pp. 1350049 ◽  
Author(s):  
M. GOVENDER
Keyword(s):  
Heat Flux ◽  
Heat Transport ◽  
Line Element ◽  
Spherically Symmetric ◽  
Spherical Collapse ◽  
Radial Heat ◽  
Heat Transport Equation ◽  
Symmetric Star ◽  
Radial Heat Flux ◽  
Two Fluid

In this paper, we present an exact model of a spherically symmetric star undergoing dissipative collapse in the form of a radial heat flux. The interior of the star is matched smoothly to the generalized Vaidya line element representing a two-fluid atmosphere comprising null radiation and a string fluid. The influence of the string density on the thermal behavior of the model is investigated by employing a causal heat transport equation of Maxwell–Cattaneo form.

scholarly journals RADIATING SPHERICAL COLLAPSE WITH HEAT FLOW

2003 ◽  
Vol 12 (04) ◽  
pp. 667-676 ◽  
Author(s):  
M. GOVENDER ◽  
K. S. GOVINDER ◽  
S. D. MAHARAJ ◽  
R. SHARMA ◽  
S. MUKHERJEE ◽  
...  
Keyword(s):  
Heat Flux ◽  
Simple Model ◽  
Gravitational Collapse ◽  
Temporal Evolution ◽  
Junction Conditions ◽  
X Ray ◽  
Spherical Collapse ◽  
Radial Heat ◽  
Cold Star ◽  
Radial Heat Flux

We present here a simple model of radiative gravitational collapse with radial heat flux which describes qualitatively the stages close to the formation of a superdense cold star. Starting with a static general solution for a cold star, the model can generate solutions for the earlier evolutionary stages. The temporal evolution of the model is specified by solving the junction conditions appropriate for radiating gravitational collapse. The results will be useful in constructing models for the evolution of X-ray pulsars, like Her X-1.

scholarly journals Collapse of a Relativistic Self-Gravitating Star with Radial Heat Flux: Impact of Anisotropic Stresses

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Ranjan Sharma ◽  
Shyam Das
Keyword(s):  
Heat Flux ◽  
Simple Model ◽  
Heat Flow ◽  
Spherically Symmetric ◽  
Local Anisotropy ◽  
Evolving Systems ◽  
Radial Heat Flow ◽  
Radial Heat ◽  
Radial Heat Flux ◽  
Collapse Rate

We develop a simple model for a self-gravitating spherically symmetric relativistic star which begins to collapse from an initially static configuration by dissipating energy in the form of radial heat flow. We utilize the model to show how local anisotropy affects the collapse rate and thermal behavior of gravitationally evolving systems.

Dissipative collapse of a Karmarkar star

2020 ◽  
Vol 35 (20) ◽  
pp. 2050164 ◽  
Author(s):  
M. Govender ◽  
A. Maharaj ◽  
Ksh. Newton Singh ◽  
Neeraj Pant
Keyword(s):  
Stellar Structure ◽  
Spherically Symmetric ◽  
Isotropic Coordinates ◽  
Radial Heat ◽  
Radiating Star ◽  
Physical Tests ◽  
Dynamical Nature ◽  
Radial Heat Flux ◽  
Radiative Collapse ◽  
Static Core

In this paper, we employ the Karmarkar condition to model a spherically symmetric radiating star undergoing dissipative gravitational collapse within the framework of classical general relativity. The collapse ensues from an initial static core satisfying the Karmarkar condition in isotropic coordinates and proceeds nonadiabatically by emitting energy in the form of a radial heat flux to the exterior Vaidya spacetime. We show that the dynamical nature of the collapse is sensitive to the initial static configuration that inherently links the embedding to the final remnant. Our model considered several physical tests on how an initially static stellar structure onset to a radiative collapse.

scholarly journals A perturbative approach to the time-dependent Karmarkar condition

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Megandhren Govender ◽  
Wesley Govender ◽  
Kevin P Reddy ◽  
Sunil D Maharaj
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Gravitational Collapse ◽  
Time Dependent ◽  
Perturbative Approach ◽  
Radial Heat ◽  
Radiating Star ◽  
Static Regime ◽  
Radial Heat Flux ◽  
Static Core

AbstractIn this work we employ a perturbative approach to study the gravitational collapse of a shear-free radiating star. The collapse proceeds from an initial static core satisfying the time-independent Karmarkar condition and degenerates into a quasi-static regime with the generation of energy in the form of a radial heat flux. The time-dependent Karmarkar condition is solved together with the boundary condition to yield the full gravitational behaviour of the star. Our model is subjected to rigorous regularity, causality and stability tests.

scholarly journals THE ROLE OF SHEAR IN DISSIPATIVE GRAVITATIONAL COLLAPSE

2014 ◽  
Vol 23 (02) ◽  
pp. 1450013 ◽  
Author(s):  
M. GOVENDER ◽  
K. P. REDDY ◽  
S. D. MAHARAJ
Keyword(s):  
Hydrostatic Equilibrium ◽  
The Core ◽  
Radial Heat ◽  
Free Case ◽  
Radiating Star ◽  
Heat Transport Equation ◽  
Physical Features ◽  
Radial Heat Flux ◽  
Collapse Process

In this paper, we investigate the physics of a radiating star undergoing dissipative collapse in the form of a radial heat flux. Our treatment clearly demonstrates how the presence of shear affects the collapse process; we are in a position to contrast the physical features of the collapsing sphere in the presence of shear with the shear-free case. By employing a causal heat transport equation of the Maxwell–Cattaneo form we show that the shear leads to an enhancement of the core temperature thus emphasizing that relaxational effects cannot be ignored when the star leaves hydrostatic equilibrium.

Sign in / Sign up

Export Citation Format

Share Document