Mode detection from line-profile variations in Delta Scuti stars

Abstract

The phenomenology associated with line profile variations in delta Scuti stars is reviewed. The three main techniques adopted to detect pulsation modes, i.e., the pixel-by-pixel analysis, the analysis of the moment time series and the Fourier Doppler Imaging are presented and discussed. Their application to the observational data has allowed the reliable detection of several pulsation modes, many of them not detectable with photometric observations. The need of better coordination of simultaneous spectroscopic and photometric campaigns in order to get the complete pulsation spectra of these stars is pointed out. The observation in different campaigns of the same objects has proved that dramatic changes in the mode amplitudes are quite common, even in a couple of years (and maybe less). In the last part of the paper a recent approach to the mode detection by direct fit of line profile variations in multiperiodic pulsators is described.