The γ Doradus CoRoT target HD 49434. II. Frequency analysis of the CoRoT data
Auvergne, M.; Amado, P. J.; Baudin, F.; Poretti, E.; Michel, E.; Garrido, R.; Rainer, M.; Rodríguez, E.; Uytterhoeven, K.; Baglin, A.; Catala, C.; Samadi, R.; Mathias, P.; Eyer, L.; Hareter, M.; Chapellier, E.; Le Contel, D.; Martín-Ruíz, S.; Paparo, M.; Bouabid, M. -P.; Díaz-Fraile, D.
France, Spain, Italy, Austria, Switzerland, Hungary
Abstract
Context. HD 49434 is a bright (V = 5.75 m) 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.