The B0.5 IVe CoRoT target HD 49330*
II. Spectroscopic ground-based observations
GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France e-mail: email@example.com
2 Royal Observatory of Belgium, 3 avenue Circulaire, 1180 Brussels, Belgium
3 Universidad de São Paulo, IAG-USP, Brazil
4 LESIA, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
5 INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy
6 Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, 18080 Granada, Spain
7 Laboratoire AIM,CEA/DSM-CNRS-Université Paris Diderot; CEA, IRFU, SAp, centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
8 Observatori Astronòmic de la Universitat de València, ED. Instituts d'Investigatió, Poligon La Coma, 46980 Paterna, València, Spain
9 Observatorio Astronomico/DEGEO, Universidade Estadual de Ponta Grossa, Brazil
Accepted: 20 May 2009
Context. We present spectroscopic ground-based observations of the early Be star HD 49330 obtained simultaneously with the CoRoT-LRA1 run just before the burst observed in the CoRoT data.
Aims. Ground-based spectroscopic observations of the early Be star HD 49330 obtained during the precursor phase and just before the start of an outburst allow us to disantangle stellar and circumstellar contributions and identify modes of stellar pulsations in this rapidly rotating star.
Methods. Time series analysis (TSA) is performed on photospheric line profiles of and by means of the least squares method.
Results. We find two main frequencies = 11.86 c d-1 and = 16.89 c d-1 which can be associated with high order p-mode pulsations. We also detect a frequency = 1.51 c d-1 which can be associated with a low order g-mode. Moreover we show that the stellar line profile variability changed over the spectroscopic run. These results are in agreement with the results of the CoRoT data analysis, as shown in Huat et al. (2009).
Conclusions. Our study of mid- and short-term spectroscopic variability allows the identification of p- and g-modes in HD 49330. It also allows us to display changes in the line profile variability before the start of an outburst. This brings new constraints for the seimic modelling of this star.
Key words: stars: early-type / stars: emission-line, Be / stars: individual: HD 49330 / stars: rotation / stars: oscillations
© ESO, 2009