Sur les déplacements radiaux de différents éléments dans α2 CVn

Résumé On compare les courbes de déplacements radiaux déduites des mesures de Struve et Swings, celles déduites des mesures de Babcock et Burd et celle d'Eu déduite des mesures de Pyper (en tenant compte de tous les résultats photométriques, on aP=5,4693±0,0001 j). Les différences sont surtout attribuables, dans le cadre du modèle binaire, à l'effet Ovenden. Celui-ci ainsi que les courants circumstellaires peuvent aussi être responsables des trop grands déplacements constatés et d'autres particularités.

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Curves of radial displacements for ² CVn are obtained by mechanical integration of radial velocity curves deduced from measures by Struve and Swings and by Babcock and Burd for Euii, Crii, Fei andii, and by Pyper for Euii.In order to proceed to the comparison, a value as accurate as possible is sought for the period. If we take all the known photometric observations into account, we get 5.4693±0.0001 d.Small differences between the curves for a given ion are noted, especially when using Pyper's measures. However these discrepancies do not necessarily prove the existence of secular variations; in the binary model, they can be interpreted mainly in terms of the Ovenden effect. Too large displacements, and other pecularities in the variations, may also be attributed to that effect, and to circumstellar currents.The ranges of the velocity variations and of the radial displacements are also discussed for other Ap stars.