Discrete Mass Ejections from the Be/X-ray Binary A0535+26/HD245770

TL;DR

This study analyzes long-term optical and X-ray data of the Be/X-ray binary A0535+26, revealing that giant X-ray outbursts are linked to mass ejection events and disk density changes in the system.

Contribution

It provides the first long-term optical spectroscopic dataset linking mass ejection events to X-ray outbursts in A0535+26.

Findings

Giant X-ray outbursts occur during optical brightness fading.

Anti-correlation between optical brightness and Hα intensity indicates mass ejection.

Mass ejection events may trigger disk loss and X-ray outbursts.

Abstract

We present the long-term optical spectroscopic observations on the Be/X-ray binary A0535+26 from 1992 to 2010. Combining with the public V-band photometric data, we find that each giant X-ray outburst occurred in a fading phase of the optical brightness. The anti-correlation between the optical brightness and the H$\alpha$ intensity during our 2009 observations indicates a mass ejection event had taken place before the 2009 giant X-ray outburst, which might cause the formation of a low-density region in the inner part of the disk. The similar anti-correlation observed around 1996 September indicates the occurrence of the mass ejection, which might trigger the subsequent disk loss event in A0535+26.