Caught in flagrante delicto: evidence for past mass transfer in massive binaries?

TL;DR

This paper reviews observational evidence for past mass transfer in massive binary systems, highlighting signatures like rapid rotation and altered surface abundances, to improve understanding of binary evolution.

Contribution

It provides a comprehensive review of observational signatures indicating past mass transfer in massive binaries, aiding the refinement of binary evolution models.

Findings

Evidence of rapid rotation in mass gainers.

Altered surface chemical abundances in donors.

Insights into mass transfer efficiency and binary evolution.

Abstract

Many massive binary systems undergo mass and angular momentum transfer over the course of their evolution. This kind of interaction is expected to deeply affect the properties of the mass donor and mass gainer and to leave various observational signatures. The most common smoking guns of a past mass transfer episode are notably rapid rotation of the mass gainer and altered surface chemical abundances of the stripped mass donor star. Quantitative observational studies of evolved massive binaries are crucial to gain insight into poorly constrained parameters of binary evolution models such as the fraction of mass lost by the mass donor that is actually accreted by the mass gainer. Yet, drawing conclusions about a past mass transfer episode requires a detailed analysis of all aspects of a binary system which sometimes leads to unexpected results. In this contribution, we review the existing observational evidence for past mass exchange events in massive main-sequence and post main-sequence binaries.