Binary interaction dominates the evolution of massive stars

TL;DR

Binary interactions are the primary factor shaping the evolution of massive stars, with over 70% experiencing mass exchange and one-third merging, significantly impacting stellar populations and supernovae.

Contribution

This study provides the first comprehensive measurement of binary interaction rates among Galactic massive stars, revealing their dominance in stellar evolution.

Findings

Over 70% of massive stars exchange mass with companions.

One-third of massive stars undergo binary mergers.

Binary interactions significantly influence stellar evolution and supernovae.

Abstract

The presence of a nearby companion alters the evolution of massive stars in binary systems, leading to phenomena such as stellar mergers, X-ray binaries and gamma-ray bursts. Unambiguous constraints on the fraction of massive stars affected by binary interaction were lacking. We simultaneously measured all relevant binary characteristics in a sample of Galactic massive O stars and quantified the frequency and nature of binary interactions. Over seventy per cent of all massive stars will exchange mass with a companion, leading to a binary merger in one third of the cases. These numbers greatly exceed previous estimates and imply that binary interaction dominates the evolution of massive stars, with implications for populations of massive stars and their supernovae.