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Astron. Astrophys. 340, 457-462 (1998)


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

B. Mosser * 1, 2, J.P. Maillard* 1, D. Mékarnia* 3 and J. Gay 3

1 IAP (CNRS, UPR 341), 98bis, bd Arago, F-75014 Paris, France (e-mail: mosser@iap.fr)
2 Université Pierre et Marie Curie, F-75252 Paris Cedex 5, France
3 Département Fresnel (CNRS, UMR 6528), Observatoire de la Côte d'Azur B.P. 4229, F-06304 Nice Cedex 4, France

Received 26 June 1998 / Accepted 29 September 1998

Abstract

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 through a bandpass chosen in the near infrared is continuously scanned. Its phase is measured and translated directly into velocity with an absolute calibration, providing a sensitive measurement of the Doppler signal.

This paper reports the 4.5 nights observation of Procyon in February 1998 with this instrumentation. The final 1-[FORMULA] noise of the spectrum beyond 0.8 mHz is as low as 0.12 m s[FORMULA]. 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 limit on the amplitude of the modes can be deduced, which cannot exceed 1 m s-1. However, the "comb response" exhibits the signature of a possible regular pattern with a large splitting [FORMULA] of 53 µHz, which would indicate that a signal of stellar origin has been detected. Both values agree with theoretical predictions, but are in contradiction with claimed detection of p -modes previously reported.

Key words: techniques: interferometric – techniques: radial velocities – stars: individual: ff CMi = Procyon – stars: oscillations

* Visiting Astronomer, Canada-France-Hawaii Telescope operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France and the University of Hawaii

Send offprint requests to: B. Mosser (mosser@iap.fr)

© European Southern Observatory (ESO) 1998

Online publication: November 9, 1998

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