Trends of Stellar Entropy along Stellar Evolution

TL;DR

This paper explores the evolution of thermodynamic entropy per baryon across various stellar objects and stages, highlighting how gravity influences entropy changes from molecular clouds to black holes.

Contribution

It provides a comprehensive analysis of entropy variation throughout stellar evolution, emphasizing the role of gravity and virial equilibrium in entropy dynamics.

Findings

Entropy per baryon decreases from molecular clouds to white dwarfs and neutron stars.

Gravitational collapse can significantly increase entropy in black holes.

Virial equilibrium influences the entropy decrease during stellar evolution.

Abstract

This paper is devoted to discuss the difference in the thermodynamic entropy budget {\it per baryon} in each type of stellar object found in Universe. We track and discuss the actual {\it decrease} of the stored baryonic thermodynamic entropy from the most primitive molecular cloud up to the final fate of matter in the black holes, passing through evolved states of matter as found in white dwarfs and neutron stars. We then discuss the case of actual stars of different masses throughout their {\it evolution}, clarifying the role of virial equilibrium condition for the decrease of the entropy and related issues. Finally, we discuss how gravity ultimately drives composition, hence structural changes along the stellar evolution all the way until the ultimate collapse to black holes, which may increase dramatically their entropy because of the gravitational contribution itself.