New limit on the p-mode oscillations of Procyon obtained by Fourier transform seismometry

The Fourier transform spectrometer based at the CFH telescope was used as a stellar accelerometer in a new seismometric mode. One fringe at a selected path difference of the interferogram produced by the flux of a star throug h a bandpass chosen in the near infrared is continuously scanned. Its phase is measured and translated directly into velocity with an absolute calibra tion, providing a sensitive measurement of the Doppler signal. This paper reports the 4.5 nights observation of Procyon in February 1998 w ith this instrumentation. The final 1-sigma noise of the spectrum beyond 0. 8 mHz is as low as 0.12 m s(-1).mu Hz(-1/2) Even with this noise level, in a single site observation we cannot report a firm detection of p-modes. We do not detect any significant excess in the power spectrum near 1 mHz. A li mit on the amplitude of the modes can be deduced, which cannot exceed 1 ms( -1). However, the "comb response" exhibits the signature of a possible regu lar pattern with a large splitting nu(0) of 53 mu Hz, which would indicate that a signal of stellar origin has been detected. Both values agree with t heoretical predictions, but are in contradiction with claimed detection of p-modes previously reported.