Adiabatic Mass Loss in Binary Stars - I. Computational Method

TL;DR

This paper introduces a computational method to model the adiabatic response of donor stars in binary systems undergoing rapid mass loss, aiding understanding of mass transfer stability and post-common envelope binaries.

Contribution

It presents a new approach to simulate adiabatic mass loss in binary stars, enabling analysis of dynamical stability and binary evolution constraints.

Findings

Validated models against time-dependent calculations.

Quantified conditions for dynamical mass transfer.

Established energy limits for post-common envelope binaries.

Abstract

The asymptotic response of donor stars in interacting binary systems to very rapid mass loss is characterized by adiabatic expansion throughout their interiors. In this limit, energy generation and heat flow through the stellar interior can be neglected. We model this response by constructing model sequences, beginning with a donor star filling its Roche lobe at an arbitrary point in its evolution, holding its specific entropy and composition profiles fixed as mass is removed from the surface. The stellar interior remains in hydrostatic equilibrium. Luminosity profiles in these adiabatic models of mass-losing stars can be reconstructed from the specific entropy profiles and their gradients. These approximations are validated by comparison with time-dependent binary mass transfer calculations. We describe how adiabatic mass loss sequences can be used to quantify threshold conditions for dynamical time scale mass transfer, and to establish the range of post-common envelope binaries that are allowed energetically.