2006A&A...453.1041J

We present high resolution spectroscopic observations of the γ Doradus star HD195068. About 230 spectra were collected over 2 years. Time series analysis performed on radial velocity data shows a main peak at 1.61d^–1, a frequency not yet detected in photometry. The Hipparcos photometric 1.25d^–1 frequency is easily recovered as is 1.30d^–1 while the third photometric frequency, 0.97d^–1, is only marginally present. The good quality of our data, which includes 196 spectra collected over seven consecutive nights, shows that both the 1.61d^–1 and intermediate 1.27d^–1 (mixture of 1.25 and 1.30d^–1) frequencies are present in the line profile variations. Using the Fourier-Doppler Imaging (FDI) method, the variability associated with 1.61d^–1 can be successfully modeled by a non-radial pulsation mode l=5±1, |m|=4±1. For the intermediate frequency 1.27d^–1 we deduce l=4±1, |m|=3±1. Evidence that the star is not pulsating in the radial mode (l=0) rules out a previous classification as an RR Lyrae type star. We investigate the time variability of FDI power spectra concluding that the observed temporal variability of modes can be explained by a beating phenomenon between closely spaced frequencies of two non-radial modes. The distribution of the oscillation power within the line profile indicates that there is a significant tangential velocity component of oscillations characteristic of high radial order gravity modes which are predicted to be observed in γ Doradus type stars.