Multiplicity in 5 Msun Stars

TL;DR

This paper reviews how multiplicity affects 5 solar mass stars throughout their evolution, highlighting the importance of binary and multiple systems in understanding stellar properties and evolution.

Contribution

It synthesizes recent observational findings on binary properties of 5 solar mass stars, emphasizing the role of multi-wavelength data in characterizing these systems.

Findings

High fraction of triple systems among 5 Msun stars

Distribution of mass ratios in Cepheids informs binary evolution

X-ray data reveal low-mass companions and their youth

Abstract

Binary/multiple status can affect stars at all stages of their lifetimes: evolution onto the main sequence, properties on the main sequence, and subsequent evolution. 5 $M_\odot$ stars have provided a wealth of information about the binary properties fairly massive stars. The combination of cool evolved primaries and hot secondaries in Cepheids (geriatric B stars) have yielded detailed information about the distribution of mass ratios. and have also provided a surprisingly high fraction of triple systems. Ground-based radial velocity orbits combined with satellite data from Hubble, FUSE, IUE, and Chandra are needed to provide full information about the systems, including the masses. As a recent example, X-ray observations can identify low mass companions which are young enough to be physical companions. Typically binary status and properties (separation, eccentricity, mass ratio) determine whether any stage of evolution takes an exotic form.