Pulsations in the late-type Be star HD 50 209 detected by CoRoT
Auvergne, M.; Poretti, E.; Michel, E.; Garrido, R.; Rainer, M.; Uytterhoeven, K.; Catala, C.; Samadi, R.; Frémat, Y.; Neiner, C.; Janot-Pacheco, E.; Floquet, M.; Martayan, C.; Emilio, M.; Gutiérrez-Soto, J.; Huat, A. -L.; Hubert, A. -M.; de Batz, B.; Leroy, B.; Andrade, L.; Diago, P. D.; Fabregat, J.; Semaan, T.; Suso, J.; Espinosa Lara, F.
Spain, France, Belgium, Brazil, Italy
Abstract
Context: The presence of pulsations in late-type Be stars is still a matter of controversy. It constitutes an important issue to establish the relationship between non-radial pulsations and the mass-loss mechanism in Be stars.
Aims: To contribute to this discussion, we analyse the photometric time series of the B8IVe star HD 50 209 observed by the CoRoT mission in the seismology field.
Methods: We use standard Fourier techniques and linear and non-linear least squares fitting methods to analyse the CoRoT light curve. In addition, we applied detailed modelling of high-resolution spectra to obtain the fundamental physical parameters of the star.
Results: We have found four frequencies which correspond to gravity modes with azimuthal order m=0,-1,-2,-3 with the same pulsational frequency in the co-rotating frame. We also found a rotational period with a frequency of 0.679 cd-1 (7.754 μHz).
Conclusions: HD 50 209 is a pulsating Be star as expected from its position in the HR diagram, close to the SPB instability strip.