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

T. R. Bedding (1) , H. Kjeldsen (2) , François Bouchy (3) , H. Bruntt (2, 4) , R. P. Butler (5) , D. L. Buzasi (4) , J. Christensen-Dalsgaard (2) , S. Frandsen (2) , Jean-Claude Lebrun (6) , Milena Martic (6) , J. Schou (7)

1 School of Physics [Sydney]
2 Department of Physics and Astronomy [Aarhus]
3 LAM - Laboratoire d'Astrophysique de Marseille
4 USAFA - Department of Physics of the US Air Force Academy
5 Department of Terrestrial Magnetism [Carnegie Institution]
6 SA - Service d'aéronomie
7 HEPL - Hansen Experimental Physics Lab [Stanford]

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 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.

Domaines: Astrophysique [astro-ph]

T. R. Bedding, H. Kjeldsen, François Bouchy, H. Bruntt, R. P. Butler, et al.. The non-detection of oscillations in Procyon by MOST: Is it really a surprise?. Astronomy and Astrophysics - A&A, 2005, 432 (2), pp.L43-L48. ⟨10.1051/0004-6361:200500019⟩. ⟨hal-00080658⟩