I am primarily involved in time resolved studies of binary star systems, using the Liverpool Telescope and other ground based optical/infrared facilities. The subject of my PhD was the optical emission from Ultraluminous X-ray Sources, which are a class of extremely X-ray bright black hole binaries. These are of interest because the black holes (in some of them at least) might be of intermediate mass (100 - 1,000,000 solar masses), bridging the gap between the better understood populations of stellar-mass and supermassive black holes.

These days I am more interested in Galactic white dwarf binaries, in particular the accreting systems known as Cataclysmic Variables. The eclipsing examples are particularly powerful tools for precise study, and I have done a lot of work in this area using the fast photometer ULTRACAM. Of particular interest to me are the ultracompact binaries known as AM CVn stars. These systems have orbital periods of the order of tens of minutes or less, and consist of a white dwarf accreting matter from a donor star that is itself at least partially degenerate. These rare systems are powerful tools for the study of binary evolution.