Advances in Astrophysics

AdAp
>
Volume 5, Number 2, May 2020

Functions and Relations for a Relativistic Evolving Star with Spherical Symmetry
DOI:

10.22606/adap.2020.52001
**Author(s)**
Ying-Qiu Gu

**Affiliation(s)**
School of Mathematical Science, Fudan University, Shanghai 200433, China

**Abstract**
In this paper, we derive and simplify some important equations and relations for a
relativistic evolving star with spherical symmetry, and then give some simple analysis for their
properties and implications. In the light-cone coordinate system, these equations and relations
have a normal and neat form which is much more accessible than the usual Einstein field equation.
The dynamics for the evolving star is reduced to a standard first order hyperbolic partial differential
equation system of (ρ, v), which can be analyzed and solved by characteristic method. So they may
be helpful to understand the nature of an evolving star and the collapsing process of gravitation.

**Keywords**
stellar structure, stellar evolution, Einstein’s field equation, relativistic evolving equation,
singularity.

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