The Multiplicity of High-Mass Stars

TL;DR

This study investigates the multiplicity of high-mass stars, revealing a decreasing binary fraction with lower mass and suggesting specific formation processes for these systems.

Contribution

It provides new empirical data on the binary fraction of high-mass stars and insights into their formation mechanisms.

Findings

Multiplicity rate drops from 80% to 20% with decreasing mass.

Close binary systems often have similar-mass components.

High multiplicity necessitates revised photometric calibrations.

Abstract

We report about an ongoing photometric and spectroscopic monitoring survey of about 250 O- and 540 B-type stars in the southern Milky Way with the aim to determine the fraction of close binary systems as a function of mass and to determine the physical parameters of the individual components in the multiple systems. Preliminary results suggest that the multiplicity rate drops from 80% for the highest masses to 20% for stars of 3 solar masses. Our analysis indicates that the binary systems often contain close pairs with components of similar mass. This coincidence cannot originate from a random tidal capture in a dense cluster but is likely due to a particular formation process for high-mass stars. The large percentage of multiple systems requires a new photometric calibration for the absolute magnitudes of O-type stars.