A study of the Hbeta profiles and pulsation of the envelope of the Be star HD 218393.

A study of the radial velocity curve for lines produced by the envelope of HD 218393 has shown: 1) the expansion is accelerated during all the period, but the acceleration decreases progressively from the maximum to the minimum of the radial velocity curve; 2) the acceleration of the deeper layers is greater than that of higher layers. One can conclude that the motion originates in parts of the envelope near the surface of the star. The structure of the H p profile is correlated with the phase of the radial velocity variation. Key words: Be star - radial velocity - line profile L'e'tude de la courbe des vitesses radiales des raies d'enveloppe de HD 218393 permet de montrer que: 1) l'expansion suit une loi de mouvement acc6l6r6 pendant tout le cycle, mais l' ation diminue progressivement du maximum au minimum des courbes de vitesse radiale. 2) les couches les plus profondes subissent des acce'l6rations plus importantes que les couches superficielles. Il en que les mouvements prennent naissance dans les r6gions de l'enveloppe proches de la surface de l' toile. Les profils de la raie H p une corr6lation avec la phase de variation des courbes de vitesse radiale.