Search for small-amplitude oscillations in stars by a Fabry-Perot interferometer

A very accurate measurement of radial velocity variations for the solar type star α CMi and the two cool Ap stars β CrB and HR 1217 has been attempted using a Fabry-Perot interferometer. The capability of this instrument has been extensively examined. No significant variation over the 13-m s-1 level has been found in the periodgram of α CMi. This proves that our Fabry-Perot system is stable at the 13-m s-1 level. The period analysis of the two cool Ap stars has shown the existence of some significant variations above the 3σ-level of noise in these stars. There appears a significant signal with a period of about 6 min in β CrB. In HR 1217, the two component of the period of 3.4 and 6.1 min have been recognized above the 3σ-level of noise. These results will be compared with the relevant photometric ones. (author)