Pulsations in the late-type Be star HD 50 209 detected by CoRoT ^*,**,***

¹ Observatori Astronòmic de la Universitat de València, Edifici Instituts d'Investigació, Polígon La Coma, 46980 Paterna, València, Spain e-mail: Pascual.Diago@uv.es
² GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, Place Jules Janssen, 92195 Meudon Cedex, France
³ LESIA, Observatoire de Paris, CNRS, Université Paris Diderot, Place Jules Janssen, 92195 Meudon Cedex, France
⁴ Royal Observatory of Belgium, 3 avenue Circulaire, 1180 Brussels, Belgium
⁵ Instituto de Astrofísica de Andalucía (CSIC), Camino Bajo de Huétor 24, 18008 Granada, Spain
⁶ Universidade de São Paulo, Instituto de Astronomia, Geofísica e Ciências Atmosféricas – IAG, Departamento de Astronomia, Rua do Matão 1226, 05508-900 São Paulo, Brazil
⁷ Observatório Astronômico/DEGEO, Universidade Estadual de Ponta Grossa, Av. Carlos Cavalcanti, 4748 Ponta Grossa, Paraná, Brazil
⁸ INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy
⁹ Instituto de Astrofísica de Canarias, Calle Via Láctea s/n, 38205 La Laguna (TF), Spain

Received: 20 February 2009
Accepted: 12 June 2009

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 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.