Astronomy Colloquium

A star interacting with a massive black hole cannot be treated as a point mass if it gets too close to the black hole that it becomes vulnerable to tidal distortions and even disruption. When a rapidly changing tidal force starts to compete with a star s self-gravity, the material of the star responds on a complicated way, being stretched along the orbital direction, squeezed at right angles to the orbit and strongly shocked. This phenomenon poses an as yet unmet challenge to computer simulations. The art of modeling tidal disruption of stars, especially those entering the strong relativistic regime, forms the main theme of my talk. Detailed simulations should tell us what happen when stars of different types get tidally disrupted, and what radiation a distant observer might detect as the observational signature of such events.