Beta Pic-like circumstellar disk gas surrounding HR 10 and HD 85905

Abstract

We present high spectral resolution observations of the absorption lines of CaII and NaI associated with the circumstellar gas disk surrounding the two A-type shell stars HR 10 and HD 85905. Data taken over two four-night periods in January and November 1997 reveal substantial changes in the circumstellar absorption line profiles between successive observations of both stars. Such variable features have both blue and red-shifted velocities up to 50 km s-1 away from the central absorbing component, and are similar to those routinely observed in the [FORMULA] Pictoris system. The sporadic presence of the circumstellar absorption components observed towards both HR 10 and HD 85905 may be explained by the infalling evaporating comet model developed for the [FORMULA] Pictoris system by Beust et al. (1990). We note that variable circumstellar absorption features have also been detected in rapidly rotating A-type stars, such that they may be suffering irregular mass-loss that could give rise to similar circumstellar disks and shells

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