STAR-DISK COLLISIONS AND THE ORIGIN OF THE BROAD LINES IN QUASARS

Quasars and other active galactic nuclei (AGNs) are most likely powered by a massive black hole surrounded by an accretion disk and inhabiting the core of a dense stellar cluster. Star orbits intersect the disk. Hence, star-disk collisions are a daily (if not more frequent) occurrence. We consider the consequences of such collisions and show that the ''star tails'' of the disk material, accelerated by the encounter with the passing star, can travel well above the disk and, therefore, are a natural candidate for the observed broad emission-line regions.