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by Maxime Viallet - 8 April 2008

Hi ! Welcome to my brand new home page at the Strasbourg Observatory. I am currently doing my Ph.D. on the outburst model of dwarf novae and soft X-ray transients. You will find in the following a short overview of my research interests.

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Overview of an interacting binary system

During my PhD, I work on interacting binary systems showing outbursts. These systems are dwarf novae and soft X-ray transients. Both types of systems are low mass binary system where a late type mass donor star looses matter by Roche lobe overflow. The gas then forms a disc around the compact object, which is a white dwarf in dwarf novae (so these systems are part of the cataclysmic variable family) and either a neutrons star or a black hole in soft X-ray transients (so these systems are part of the low mass X-ray binaries family).

Both kind of systems show outbursts, which are sudden and bright increases of the luminosity of the system. Outbursts are best explained by a disc instability model involving a thermal/viscous instability triggered when hydrogen becomes partially ionized in the disc. In this picture, the disc is constantly switching between quiescent state where it fills up and outburst state where mass accretion in the disc and on the compact objet are greatly enhanced.

Despite the success of the model, there is still some features of observed lightcurves that are not easily reproduced by the "standard model". I am interested in the possiblity of an enhanced mass transfer rate during outburst. This is the most famous "additional ingredient" that people introduces in the model to improve its predictions. Still, yet there is no physical model explaining why and how mass transfer rate is increased. This is why I’m doing a PhD on that topic ! I try my best to make a first step toward a physical model of mass transfer enhancement mechanisms. Check my related papers for more science.

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