| NEW RADIAL VELOCITY CURVES OF roAp AND (2007) | |||||||||||||
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| We present new radial velocity curves of the rapidly oscillating Ap (roAp) star, ff Cir, and the ffi Scuti star, FG Vir, obtained from multisite observations with medium-dispersion spectrographs. The velocity curves are found by using a cross-correlation technique on the H ff line and some metal lines, with the (terrestrial) atmospheric absorption band around 6900 A used as a reference. In ff Cir, we have found some unexpected results where the amplitude and phase of the main pulsation mode varies significantly depending on which line is being measured. 1. INTRODUCTION Our inability to identify the oscillation modes, of multi-periodic stars like ffi Scuti, roAp and fi Cephei stars, has prevented useful asteroseismology. Even with 10--20 detected modes (as in FG Vir) the lack of mode identification is striking. From the discussion by Bedding et al. (1996) of different observing methods sensitivity to modes with different l-values as a function of wavelength, this suggests that one can ... | |||||||||||||
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