Construct a realistic stellar model with polytropic relation

TL;DR

This paper develops a simplified stellar model with a non-uniform polytropic index, solving separate equations for density and pressure, and demonstrates its effectiveness by comparing it to detailed models of the Sun.

Contribution

It introduces a new approach to stellar modeling that avoids the Emden equation by solving independent equations for density and pressure, enabling simpler yet accurate models.

Findings

The model accurately reproduces solar properties.

It offers a simpler alternative to standard stellar models.

The approach is effective for non-uniform polytropic indices.

Abstract

The aim of this study is to construct a simple stellar model with non-uniform polytropic index. We find that the Emden equation cannot deal with the polytrope gas sphere with non-uniform polytropic index in a real star, and then we construct a realistic stellar model. The key point is that we should solve the two independent equations for density and pressure due to the essence of polytropic relation, but not the Emden equation which combines the hydrostatic balance and polytropic relation. We take the Sun for a computational example to find that this simple model yields quite a good result compared to the MESA code. The advantage of this simple model lies in its much simpler equation of state than that in the standard stellar model.