Broad emission lines of QSOs are consistent with rotating supermassive stars

Quasars and Seyfert galaxies typically have optical and UV spectra characterized by a largely nonthermal continuum, narrow emission lines, and broad emission lines observed only in permitted and intercombination transitions. The broad lines come from a small amount of dense, fast-moving gas. The origin, geometry, and dynamics of the broad line gas are uncertain. It is suggested here that the basic properties of the broad emission-line profiles are consistent with emission from the surface of a rotating, supermassive star. (author)