Sur les déplacements radiaux de différents éléments dans alpha2 CVn

Curves of radial displacements for alpha2 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 and II, 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 peculiarities 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.