Evolution of dense galactic nuclei through dwarf star collisions

Abstract

STELLAR collisions are important in dense galactic nuclei1–3. QSOs, N galaxies and Seyfert galaxies release energy on similar short time scales4–7 but detailed models of stellar collisions have been limited so far to collisions between two main sequence stars, with the conclusion that for an initial relative velocity Vrel ≲ 103 km s−1, and small impact parameter, coalescence follows. At Vrel ∼ 5,000 km s−1 two colliding main sequence stars are largely disrupted and a non-negligible amount of relativistic particles is formed8. Here we draw attention to the fact that a very important type of collision in dense galactic nuclei is one in which a white dwarf (WD) is involved.