The beta Pictoris circumstellar disk. V. Time variations of the Ca II-K line.

Observations of the Ca II-K line profile in β Pictoris (A5 V) at different epochs show drastic changes on time scales of months, days and hours. At the center of the stellar line, a relatively stable narrow absorption feature is present while, on its red wing, absorptions can appear and disappear. These changes could be related either to a "classical" shell very close to the star or to the much more extended circumstellar dust disk present around β Pic. In this last case, they may be related to cometary-like objects falling on the star.