The CoRoT B-type binary HD50230: a prototypical hybrid pulsator with g-mode period and p-mode frequency spacings

TL;DR

This paper analyzes the hybrid pulsator HD50230 using CoRoT data and spectroscopy, identifying its binary nature, pulsation modes, and rotational characteristics to aid asteroseismic modeling.

Contribution

It provides a detailed observational characterization of HD50230, including its binary status, pulsation modes, and rotational properties, enhancing the understanding of hybrid B-type pulsators.

Findings

HD50230 is a spectroscopic binary with two components.

Simultaneous high-order g modes and low-order p and g modes detected.

Estimated surface rotation rate and inclination angle.

Abstract

B-type stars are promising targets for asteroseismic modelling, since their frequency spectrum is relatively simple. We deduce and summarise observational constraints for the hybrid pulsator, HD50230, earlier reported to have deviations from a uniform period spacing of its gravity modes. The combination of spectra and a high-quality light curve measured by the CoRoT satellite allow a combined approach to fix the position of HD50230 in the HR diagram. To describe the observed pulsations, classical Fourier analysis was combined with short-time Fourier transformations and frequency spacing analysis techniques. Visual spectra were used to constrain the projected rotation rate of the star and the fundamental parameters of the target. In a first approximation, the combined information was used to interpret multiplets and spacings to infer the true surface rotation rate and a rough estimate of the inclination angle. We identify HD50230 as a spectroscopic binary and characterise the two components. We detect the simultaneous presence of high-order g modes and low-order p and g-modes in the CoRoT light curve, but were unable to link them to line profile variations in the spectroscopic time series. We extract the relevant information from the frequency spectrum, which can be used for seismic modelling, and explore possible interpretations of the pressure mode spectrum.