A 0535+26: back in business

Abstract

In 2005 May/June, after 10 yr of inactivity, the Be/X-ray binary system A 0535+26 underwent a major X-ray outburst. In this paper, data are presented from 10 yr of optical, infrared and X-ray monitoring showing the behaviour of the system during the quiescent epoch and the lead up to the new outburst. The results show the system going through a period when the Be star in the system had a minimal circumstellar disc and then a dramatic disc recovery leading, presumably, to the latest flare up of X-ray emission. The data are interpreted in terms of the state of the disc and its interaction with the neutron star companion.