Multiplicity of massive O stars and evolutionary implications

TL;DR

This study investigates the binary characteristics of massive O stars in young clusters, revealing a high binary fraction, preference for short periods, and significant mass exchange, which profoundly impacts their evolution.

Contribution

It provides the first comprehensive measurement of intrinsic binary properties of massive stars, highlighting the high interaction rate and challenging previous assumptions about binary distributions.

Findings

Over 70% of massive stars exchange mass with companions.

Binary systems favor short orbital periods and have a flat mass-ratio distribution.

No significant peak of equal-mass 'twin' binaries was found.

Abstract

Nearby companions alter the evolution of massive stars in binary systems. Using a sample of Galactic massive stars in nearby young clusters, we simultaneously measure all intrinsic binary characteristics relevant to quantify the frequency and nature of binary interactions. We find a large intrinsic binary fraction, a strong preference for short orbital periods and a flat distribution for the mass-ratios. Our results do not support the presence of a significant peak of equal-mass `twin' binaries. As a result of the measured distributions, we find that over seventy per cent of all massive stars exchange mass with a companion. Such a rate greatly exceeds previous estimates and implies that the majority of massive stars have their evolution strongly affected by interaction with a nearby companion.