Rotation and massive close binary evolution

TL;DR

This paper reviews how rotation influences the evolution of massive close binary systems, emphasizing the effects of accretion-induced spin-up and questioning the necessity of rotation in single star models.

Contribution

It provides an overview of rotational effects in massive binaries and discusses their observable consequences, challenging the role of rotation in single star evolution models.

Findings

Rotation causes critical spin-up in accreting stars.

Observable consequences of rotation are significant in binary evolution.

The necessity of rotation in single star models is questioned.

Abstract

We review the role of rotation in massive close binary systems. Rotation has been advocated as an essential ingredient in massive single star models. However, rotation clearly is most important in massive binaries where one star accretes matter from a close companion, as the resulting spin-up drives the accretor towards critical rotation. Here, we explore our understanding of this process, and its observable consequences. When accounting for these consequences, the question remains whether rotational effects in massive single stars are still needed to explain the observations.