The beta Pictoris circumstellar disk. VI. Evidence for material falling on to the star.

Abstract

New archive observations with International Ultraviolet Explorer are used to study the temporal variations of the circumstellar absorption towards β Pictoris. The authors first show that strong variations occur in the redshifted part of the resonance lines of Al III, Mg II, and Fe II, and also of metastable lines of Fe II. These variations are then studied in detail; they suggest that large amounts of gas sometimes fall on to the star, with high velocities. Some possible interpretations are discussed and seem to support the idea that the β Pic circumstellar disk could be populated by solid bodies of few kilometers size.