20 CVn:: A monoperiodic radially pulsating δ Scuti star

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