Chameleon stars

TL;DR

This paper explores static, spherically symmetric star models with a scalar field non-minimally coupled to matter, revealing significant structural changes and potential instability in such configurations.

Contribution

It introduces new solutions for gravitating scalar fields coupled to matter, highlighting their impact on star structure and stability.

Findings

Non-minimal coupling alters matter distribution within stars.

Total mass of stars is significantly affected by the coupling.

Solutions are found to be unstable under the tested parameters.

Abstract

We consider a gravitating spherically symmetric configuration consisting of a scalar field non-minimally coupled to ordinary matter in the form of a perfect fluid. For this system we find static, regular, asymptotically flat solutions for both relativistic and non-relativistic cases. It is shown that the presence of the non-minimal interaction leads to substantial changes both in the radial matter distribution of the star and in the star's total mass. A simple stability test indicates that, for the choice of parameters used in the paper, the solutions are unstable.