Astrotomography uses occultations, time delays, and Doppler shifts to make images of objects too small to be seen directly. Much of the astrophysics research at St Andrews involves the development and use of these techniques.
Accretion discs are nature's remedy for the angular momentum barrier.
As gravity pulls matter together, angular momentum should halt the contraction, and must somehow be dispersed before compact objects like stars, planets, and black holes can form. We see the gas in accretion disks spiralling inward, rather than orbiting forever, and we don't yet understand how this works. Keith Horne T Tauri stars are young solar-type stars that are still surrounded by flattened, dusty discs of protoplanetary material. Theoretical and observational work at St Andrews is focused on the region where the orbiting disc material collides with the stellar magnetic field. We use tomographic imaging methods to map the hotspots where gas flows impact the stellar surface, to improve our understanding of the way in which star-disc interactions regulate the spin of young stars.