CoRoT sounds the stars: p-mode parameters of Sun-like oscillations on HD 49933

Context. The first asteroseismology results from CoRoT are presented, on a star showing Sun- like oscillations. We have analyzed a 60 day lightcurve of high- quality photometric data collected by CoRoT on the F5V star HD 49933. The data reveal a rich spectrum of overtones of low- degree p modes. Aims. Our aim was to extract robust estimates of the key parameters of the p modes observed in the power spectrum of the lightcurve. Methods. Estimation of the mode parameters was performed using maximum likelihood estimation of the power spectrum. A global fitting strategy was adopted whereby 15 mode orders of the mode spectrum (45 modes) were fitted simultaneously. Results. The parameter estimates that we list include mode frequencies, peak linewidths, mode amplitudes, and a mean rotational frequency splitting. We find that the average large frequency (overtone) spacing derived from the fitted mode frequencies is 85.9 +/- 0.15 mu Hz. The frequency of maximum amplitude of the radial modes is at 1760 mu Hz, where the observed rms mode amplitude is 3.75 +/- 0.23 ppm. The mean rotational splitting of the non- radial modes appears to be in the range approximate to 2.7 mu Hz to approximate to 3.4 mu Hz. The angle of inclination o. ered by the star, as determined by fits to the amplitude ratios of the modes, appears to be in the range approximate to 50 degrees to approximate to 62 degrees.