The Evolutionary State of the Massive Interacting Binary BD+36 4063

TL;DR

This paper analyzes the massive binary BD+36 4063, revealing it is in a rare rapid mass transfer phase with a thick disk obscuring the companion, providing insights into early stages of massive binary evolution.

Contribution

It presents the first detailed spectroscopic and photometric analysis of BD+36 4063 during a rapid mass transfer stage, highlighting its unique evolutionary state.

Findings

The visible star is undergoing rapid mass transfer with a surrounding opaque disk.

The system has a near-unity mass ratio.

BD+36 4063 may be the first observed system at this rapid evolutionary stage.

Abstract

We present a spectroscopic and photometric analysis of the remarkable massive binary system, BD +36 4063. We argue that the visible ON star is undergoing a rapid mass transfer episode that results in a thick and opaque disk that surrounds and renders invisible its massive companion. A comparison of the projected rotational velocity and the orbital semiamplitude of the visible star indicates a mass ratio near unity. Models for conservative mass transfer show that the equal mass state occurs at the point of minimum separation, and we argue that BD +36 4063 may represent the first system identified at this rapid and rare stage of massive binary evolution.