20 CVn: A monoperiodic radially pulsating delta Scuti star

We present a new spectroscopic study of the delta Scuti star 20 CVn in orde r to solve the controversy on the type of pulsation mode of this object. Th e spectra were obtained at the Observatoire de Haute-Provence, with the Ech elle spectrograph ELODIE. Using the correlation configuration of the instru ment, sinusoidal moment variations are clearly detected, with a frequency i n perfect agreement with the photometric one. Using the moment method, we c onclude that only the radial mode is able to explain the observed moment va riations and leads to a good fit to the observed line profiles. The new dat a thus allow us to confirm the photometric results, i.e. 20 CVn exhibits a monoperiodic radial pulsation.