Regular exact models for a nonstatic gas sphere in general relativity
type: Item
instance of: scholarly article
title: Regular exact models for a nonstatic gas sphere in general relativity
zbMATH Open document ID: 0569.53042
DOI: 10.1007/BF00773619
author: Hennning Knutsen
published in: General Relativity and Gravitation
publication date: 1985-01-01T00:00:00Z
review text: Some new exact models for an expanding or a contracting ''gaseous'' sphere (i.e., the density \(\rho\) is to vanish at the outer boundary together with the pressure p) are given. The physical properties of the models are investigated, and it is found that both the pressure and the density are positive inside the outer boundary of the sphere, and their respective gradients are negative. The density is increasing for contracting spheres, and it is decreasing for expanding spheres. It is also shown that this is the case for the pressure at any moment for the layers close to the boundary of the spheres. For these layers it is further shown that the adiabatic speed of sound is less than the speed of light, and the trace of the energy-momentum tensor is positive. The rate of change of the circumference as measured by an observer riding on the boundary of the sphere is increasing for expanding spheres and it is decreasing for collapsing spheres. We also find that the ''physical radius'' is an increasing function of comoving radial coordinate. The mass function is further shown to be positive.
Mathematics Subject Classification ID: 53C80
Mathematics Subject Classification ID: 83C55
Mathematics Subject Classification ID: 83C15
zbMATH DE Number: 3909278
zbMATH Keywords: contracting spheres
zbMATH Keywords: expanding spheres
zbMATH Keywords: physical radius
MaRDI profile type: Publication
cites work: Q3896182
cites work: Some New Exact Models for the Outer Layers of a Non-Static Gas Sphere in General Relativity
cites work: ON RIEMANNTAN SPACES WITH SPHERICAL SYMMETRY ABOUT A LINE, AND THE CONDITIONS FOR ISOTROPY IN GENJ RELATIVITY
cites work: On a Class of Non-Static Perfect Fluid Spheres in General Relativity
cites work: Spherical Symmetry and Mass-Energy in General Relativity. I. General Theory
description: scientific article; zbMATH DE number 3909278