Abstract
From the analysis of 78 spectroscopic plates of the Hα emission line of 15 Be and shell stars, known to be variable from spectroscopic and photometric studies, the authors present an atlas of the Hα line. They emphasize the spectroscopic changes of the line to obtain criteria to further study the short-term variability of these interesting objects. The authors can easily detect the long-term variability comparing their Hα line observations to previous work. From this study, the authors found that all the stars observed show variability on a time scale from 2 to 14 days. On a shorter time scale, Hα line variability is present in HD 37202, HD 184279, HD 200120, HD 217050, HD 224559, HD 174638 and HD 183656. The authors include in this atlas 3 spectra of the Hα absorption line of 2 β CMa stars observed during the campain.
