1994A&A...287..564B

Fifty-two high-resolution CCD spectra (1986-1990), centered on Hα of the Herbig B3ve star HD200775 are presented and analyzed. A considerable variability of the Hα double-peak emission profile is found on timescales from days to months. The general picture of these profile variations is rather complicated, but two primary types can be distinguished, namely (i) variations of the emission line strength and (ii) positional displacements of the central absorption which range from -10 to +70 km/s. Secondary variations occur in the intensity and shape of the emission wings, the relative intensity of the red and blue emission peaks, and the position variations of the line centroid. Significant correlations between the variations of any of these profile parameters have not been found. A particular sequence of events was observed in 1986 when a slow growth of the sharp blue emission peak and a subsequent decrease of the depth of the absorption component in May-June were in July followed by the apparition of a complex structure of discrete line components in the velocity interval between -50km/s and +40km/s. This fine structure underwent considerable night-to-night variations. A qualitative interpretation of this development of the Hα profile is suggested in terms of a stellar wind which interacts with an external shell where it leads to a fragmentation of the matter into smaller clumps which are then accreted by the central star.