A fresh look at the seismic spectrum of HD49933: analysis of 180 days of CoRoT photometry

O. Benomar, F. Baudin, T. L. Campante, W. J. Chaplin, R. A. García, P. Gaulme, T. Toutain, G. A. Verner, T. Appourchaux, J. Ballot, C. Barban, Y. Elsworth, S. Mathur, B. Mosser, C. Régulo, I. W. Roxburgh, M. Auvergne, A. Baglin, C. Catala, E. Michel, R. Samadi

Abstract
Context. Solar-like oscillations have now been observed in several stars, thanks to ground-based spectroscopic observations and space-borne photometry. CoRoT, which has been in orbit since December 2006, has observed the star HD49933 twice. The oscillation spectrum of this star has proven difficult to interpret.
Aims. Thanks to a new timeseries provided by CoRoT, we aim to provide a robust description of the oscillations in HD49933, i.e., to identify the degrees of the observed modes, and to measure mode frequencies, widths, amplitudes and the average rotational splitting.
Methods. Several methods were used to model the Fourier spectrum: Maximum Likelihood Estimators and Bayesian analysis using Markov Chain Monte-Carlo techniques.
Results. The different methods yield consistent result, and allow us to make a robust identification of the modes and to extract precise mode parameters. Only the rotational splitting remains difficult to estimate precisely, but is clearly relatively large (several µHz in size).

Keywords
stars : oscillations

Notes
* The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES, with participation of the Science Programs of ESA, ESA’s RSSD, Austria, Belgium, Brazil, Germany and Spain.
** Figures 5-9 and Table 2 are only available in electronic form at http://www.aanda.org

Astronomy and Astrophysics
Volume 507, Page 13
November 2009

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