The γ Doradus CoRoT target HD 49434

II. Frequency analysis of the CoRoT data ^⋆,⋆⋆

¹ UMR 6525 H. Fizeau, UNS, CNRS, OCA, Campus Valrose, 06108 Nice Cedex 2, France
² Instituto de Astrofísica de Andalucía, CSIC, PO Box 3004, 18080 Granada, Spain
e-mail: eloy@iaa.es
³ LESIA, Observatoire de Paris, CNRS, Université Paris Diderot, 5 pl. Jules Janssen, 92190 Meudon, France
⁴ Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot; CEA, IRFU, SAp, centre de Saclay, 91191 Gif-sur-Yvette, France
⁵ Laboratoire d’Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 57 avenue d’Azereix, 65000 Tarbes, France
e-mail: Philippe.Mathias@ast.obs-mip.fr
⁶ INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Italy
⁷ Institut für Astronomie, Universität Wien, Türkenschanzstr. 17, 1180 Wien, Austria
⁸ Observatoire de Genève, Université de Genève, 1290 Sauverny, Switzerland
⁹ Konkoly Observatory, PO Box 67, 1525 Budapest, Hungary
¹⁰ Institut d’Astrophysique Spatiale, CNRS, Université Paris XI UMR 8617, 91405 Orsay, France

Received: 5 February 2010
Accepted: 15 July 2010

Abstract

Context. HD 49434 is a bright (V = 5ṃ75) and multiperiodic γ Dor-type pulsator that has been selected for the asteroseismic core programme of the CoRoT satellite.

Aims. An extensive and detailed study has been carried out to investigate the pulsational content of this object on the basis of the 136.9 d (331291 useful datapoints) time series collected by the CoRoT satellite during the long-run LRa01 (October 2007–March 2008).

Methods. The frequency analysis was carried out using the recently available software package SigSpec and Period04.

Results. The results confirm HD 49434 as a complex pulsator with a very dense pulsation spectrum. A total of 1686 significant peaks are formally detected, essentially in the region below 15 d^-1. No significant pulsation peaks are detected for frequencies higher than 30 d^-1. Solar-type oscillations are not detected in this star. The reliability of such a high number of detected peaks has been investigated on the basis of two independent methods. As a result, we propose a total of 840 frequencies that can be assumed to be intrinsic to the star.

Conclusions. The CoRoT mission provides very high-quality light curves and datasets, which are excellent for asteroseismic studies of complex pulsating stars beacause they allow investigation of the frequency content down to amplitude levels of a few μmag, unattainable with ground-based observations. In this way, hundreds of excited modes were detected in HD 49434. This is the first time that so many frequencies have been found in a γ Dor-type pulsator.