LB-1 was originally suggested to harbour a very massive (∼70M⊙) black hole, but was recently suggested to be a post-mass transfer binary containing a Be star and a helium (He) star. In this paper, we use the binary population synthesis method to simulate the potential population of the Be−He binaries in the Milky Way. Mass transfer process during the progenitor binary evolution plays a vital role in determining the possible properties of the Be−He binary population. By constructing a range of physical models with significantly different mass-transfer efficiencies, we obtain the predicted distributions at the current epoch of the component masses and the orbital periods for the Be−He binaries. In particular, we show that, LB-1 very likely has evolved through non-conservative mass transfer if it is indeed a Be−He system. We estimate that there are more than 103 Be−He binaries with V-band apparent magnitudes brighter than LB-1.
@article{arxiv.2012.06176,
title = {Population Synthesis of Galactic Be-star Binaries with A Helium-star Companion},
author = {Yong Shao and Xiang-Dong Li},
journal= {arXiv preprint arXiv:2012.06176},
year = {2021}
}