Nonconservative Mass Transfer in Massive Binaries and the Formation of Wolf-Rayet+O Binaries

TL;DR

This study models non-conservative mass transfer in massive binaries to understand the formation of Wolf-Rayet+O binaries, revealing that highly inefficient mass transfer is necessary to match observations.

Contribution

It introduces two models of non-conservative mass transfer in massive binaries and compares their outcomes with observed WR+O binaries, highlighting the need for highly inefficient transfer.

Findings

Model I shows 0.2-0.7 efficiency for Case A transfer.

Model II has about 0.2 efficiency for Case B transfer.

Highly non-conservative transfer is needed to match observations.

Abstract

The mass transfer efficiency during the evolution of massive binaries is still uncertain. We model the mass transfer processes in a grid of binaries to investigate the formation of Wolf-Rayet+O (WR+O) binaries, taking into account two kinds of non-conservative mass transfer models: Model I with rotation-dependent mass accretion and Model II of half mass accretion. Generally the mass transfer in Model I is more inefficient, with the average efficiency in a range of $\sim0.2-0.7$ and $ \lesssim0.2 $ for Case A and Case B mass transfer, respectively. We present the parameter distributions for the descendant WR+O binaries. By comparing the modeled stellar mass distribution with the observed Galactic WR+O binaries, we find that highly non-conservative mass transfer is required.