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Issue A&A
Volume 432, Number 2, March III 2005
Page(s) L43 - L48
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200500019



A&A 432, L43-L48 (2005)
DOI: 10.1051/0004-6361:200500019

Letter

The non-detection of oscillations in Procyon by MOST: Is it really a surprise?

T. R. Bedding1, H. Kjeldsen2, F. Bouchy3, H. Bruntt2, 4, R. P. Butler5, D. L. Buzasi4, J. Christensen-Dalsgaard2, S. Frandsen2, J.-C. Lebrun6, M. Martic6 and J. Schou7

1  School of Physics, University of Sydney 2006, Australia
    e-mail: bedding@physics.usyd.edu.au
2  Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark
3  Laboratoire d'Astrophysique de Marseille, Traverse du Siphon BP8, 13376 Marseille Cedex 12, France
4  Department of Physics, US Air Force Academy, 2354 Fairchild Drive, CO 80840, USA
5  Carnegie Institution of Washington, Department of Terrestrial Magnetism, Washington, DC 20015-1305, USA
6  Service d'Aéronomie du CNRS, BP 3, 91371 Verrières le Buisson, France
7  W.W. Hansen Experimental Physics Laboratory, Stanford University, 445 Via Palou, Stanford, CA 94305-4085, USA

(Received 6 August 2004 / Accepted 28 January 2005 )

Abstract
We argue that the non-detection of oscillations in Procyon by the MOST satellite reported by Matthews et al. (2004), is fully consistent with published ground-based velocity observations of this star. We also examine the claims that the MOST observations represent the best photometric precision so far reported in the literature by about an order of magnitude and are the most sensitive data set for asteroseismology available for any star other than the Sun. These statements are not correct, with the most notable exceptions being observations of oscillations in $\alpha$ Cen A that are far superior. We further disagree that the hump of excess power seen repeatedly from velocity observations of Procyon can be explained as an artefact caused by gaps in the data. The MOST observations failed to reveal oscillations clearly because their noise level is too high, possibly from scattered Earthlight in the instrument. We did find an excess of strong peaks in the MOST amplitude spectrum that is inconsistent with a simple noise source such as granulation, and may perhaps indicate oscillations at roughly the expected level.


Key words: stars: oscillations -- stars: individual: Procyon -- Sun: oscillations

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© ESO 2005


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