β Pictoris: the variable CaII H & K absorptions from 1994 to 1996.

ABSTRACTWe present high-resolution spectroscopy of the variable Ca II H & K absorptions in the star β Pictoris. 313 spectra were obtained on 53 nights between 1994 November and 1996 December in order to characterize the behaviour of the lines and to test the falling evaporating bodies (FEB) scenario. Near-continuous absorption activity was seen, including blueshifted features, one of which rivalled the strength of that reported in 1997 June by Crawford, Beust & Lagrange. Redshifted features at ∼ 5--20 km s-1 were present until the end of 1995, and are evocative of a year-long stream of infalling bodies with typically 4--5 objects in the line of sight. At higher velocities, features were shorter lived and generally broader and shallower. These correlations also apply to blueshifted features. On 1995 June 9 we detected a probable narrow, short-lived feature at a redshift of ∼ 130 km s-1. The FEB models predict that the strength of the H line may exceed the K line value as a body tracks across the stellar disc, but we have no convincing observation of this, although we did observe some events during which the H & K absorptions evolved differently. [ABSTRACT FROM AUTHOR]