Tom Marsh obituary

Astronomer who explored how a white dwarf star and a normal one can interact to provide surges in brightness or a supernova

Tom Marsh, the founding professor of the astronomy and astrophysics group at Warwick University, who has died aged 60, was a world-leading expert on compact binary star systems, two stars closely orbiting around each other. It is believed that the majority of stars are in fact in binary systems, with some close enough to produce complex interactions.

As the two stars orbit each other, we see them alternately receding from us and coming towards us. When the light from the stars is spread out into a spectrum of wavelengths, we see the features in the stellar spectra moving backwards and forwards in wavelength as they are redshifted and blueshifted by the Doppler effect. Detailed observations allow astronomers to estimate the masses of the stars, and - if the stars happen to be lined up so that they eclipse each other - their radii, and the distance of the system.