Tom Marsh obituary

Tom Marsh, the founding professor of the astronomy and astrophysics group at the University, died at the age of 60. It is thought that most of the stars are in systems with complex interactions.

The two stars are coming towards us as they circle each other. When the light from the stars is spread out into a spectrum of wavelength, we can see the stars' features moving backwards and forwards in wavelength. Calculating the mass of the stars is possible if the stars are lined up so that they eclipse each other.

One of the stars is a white dwarf, a dead compact object that represents the end-point for a star like the sun, while the other is a regular star. The normal star is forced to funnel material towards the white dwarf if it's close enough. The material forms a disc around the white dwarf.

A thermonuclear flash can be caused by material falling onto the white dwarf from the inner edge of the disc. The white dwarf systems are called Cataclysmic Variables. The white dwarf may blow up if enough material is dumped on it.

He studied white dwarfs with every telescope and instrument he could find. He invented a technique called Doppler tomography, in which the shape of the emission lines is modeled to create an image of the system and the accretion disc of gas and other matter. The image reconstruction technique provides an effective resolution which beats the "seeing" or twinkling effect of the earth's atmosphere and even the "diffraction limit" set by the wave theory of light.

He and his team used this technique to apply it to hundreds of star systems, as well as to systems with black holes. Two-arm spiral shocks seen in the accretion disc and cases where the strong magnetic field of the white dwarf channels a twisting flow of gas directly from the companion onto the white dwarf were highlights. The Herschel medal was awarded to Marsh for his contributions to the field of astronomy.

He loved to observe on the great telescopes around the world, but he also had an interest in the data analysis techniques and in the instrument needed to capture the best data. In 2007, he and his team, along with colleagues from Edinburgh Observatory, developed the Ultra cam instrument. The William Herschel Telescope on La Palma in the Canary Islands is one of the places where this camera has been used. During an observing trip at La Silla in September, Marsh went missing and was found dead in the desert a few miles away from the observatory.

Tom was the third of four children of Prudence, a teacher, and David, a systems engineer, and he was born in Old Windsor, Berks. He was given a telescope and a book when he was a kid. He studied natural sciences at Queens' College in Cambridge after graduating from St Paul's school in Barnes.

The topic of emission lines in cataclysmic variable stars became his life's work after he stayed at Cambridge. There were posts at the Royal Greenwich Observatory, Herstmonceux, and the Space Telescope Science Institute. He took up the fellowship at Oxford and then at the University ofSouthampton.

In 2003 he moved to the department of physics at the university to start an astronomy research group that has grown to 75 people. He gave up the leadership of the group in 2020 in order to get more time to look at telescopes and discover new planets. He became interested in multi-messenger astronomy, in which signals from different sources are combined to form a single signal.

He married a writer and editor in 1987. Tabetha and Henry were their children.