Mass loss out of close binaries

TL;DR

This study models mass loss in close binary systems with B-type primaries, comparing conservative and liberal evolution scenarios to understand their impact on the distribution of Algol-type binaries.

Contribution

It introduces a simulation of mass loss during fast mass transfer in binaries, incorporating liberal evolution to better match observed distributions of Algol systems.

Findings

Simulated orbital period distribution aligns well with observations.

Mass-ratio distribution shows fewer high-mass-ratio Algols than observed.

Liberal evolution slightly increases high mass-ratio systems but remains insufficient.

Abstract

In a liberal evolutionary scenario, mass can escape from a binary during eras of fast mass transfer. We calculate the mass lost by binaries with a B-type primary at birth where mass transfer starts during hydrogen core burning of the donor. We simulate the distribution of mass-ratios and orbital periods for those interacting binaries. The amount of time the binary shows Algol characteristics within different values of mass-ratio and orbital period has been fixed from conservative and liberal evolutionary calculations. We use these data to simulate the distribution of mass-ratios and orbital periods of Algols with the conservative as well as the liberal model. We compare mass-ratios and orbital periods of Algols obtained by conservative evolution with those obtained by our liberal model. Since binaries with a late B-type primary evolve almost conservatively, the overall distribution of mass-ratios will only yield a few Algols more with high mass-ratios than conservative calculations do. Whereas the simulated distribution of orbital periods of Algols fits the observations well, the simulated distribution of mass-ratios produces always too few systems with large values.