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

TL;DR

This study analyzes CoRoT photometry and high-resolution spectra of the B2.5V star HD 48977, identifying multiple pulsation modes and fundamental parameters, and highlights its classification as a Slowly Pulsating B star with potential for future asteroseismic modeling.

Contribution

It provides the first detailed characterization of HD 48977's pulsation modes and fundamental parameters using combined photometry and spectroscopy, expanding knowledge of B star instability strips.

Findings

Detected numerous high-order g-modes and a rotational frequency.

Determined fundamental parameters: Teff = 20000 ± 1000 K, log(g) = 4.2 ± 0.1.

Classified HD 48977 as a new Slowly Pulsating B star.

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 present in the light curve. We perform 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 Teff = 20000 $\pm$ 1000 K and log(g)=4.2 $/pm$ 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.