High-precision CoRoT space photometry and fundamental parameter determination of the B2.5V star HD 48977

¹ Institut d’Astrophysique et de Géophysique, Université de Liège, 17 Allée du 6 Août, 4000 Liège, Belgium
e-mail: anne.thoul@ulg.ac.be
² Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
³ LESIA, Observatoire de Paris, CNRS UMR 8109, Université Pierre et Marie Curie, Université Denis Diderot, 5 place J. Janssen, 92105 Meudon, France
⁴ Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
⁵ Institut d’Astrophysique Spatiale, CNRS/Université Paris XI UMR 8617, 091405 Orsay, France
⁶ Kavli Institute for Theoretical Physics, Kohn Hall, University of California, Santa Barbara CA 93106-4030, USA

Received: 28 December 2011
Accepted: 5 December 2012

Abstract

We present the CoRoT light curve of the bright B2.5V star HD 48977 observed during a short run of the mission in 2008, as well as a high-resolution spectrum gathered with the HERMES spectrograph at the Mercator telescope. We use several time series analysis tools to explore the nature of the variations in the light curve. We performed a detailed analysis of the spectrum of the star to determine its fundamental parameters and its element abundances. We find a large number of high-order g-modes, and one rotationally induced frequency. We find stable low-amplitude frequencies in the p-mode regime as well. We conclude that HD 48977 is a new slowly pulsating B star with fundamental parameters found to be T_eff = 20   000 ± 1000 K and log g = 4.2 ± 0.1. The element abundances are similar to those found for other B stars in the solar neighbourhood. HD 48977 was observed during a short run of the CoRoT satellite implying that the frequency precision is insufficient to perform asteroseismic modelling of the star. Nevertheless, we show that a longer time series of this star would be promising for such modelling. Our present study contributes to a detailed mapping of the instability strips of B stars in view of the dominance of g-mode pulsations in the star, several of which occur in the gravito-inertial regime.