Pulsations in the late-type Be star HD 50209 detected by CoRoT

TL;DR

This study confirms the presence of gravity-mode pulsations in the late-type Be star HD 50209 using CoRoT photometry, supporting the link between pulsations and mass-loss mechanisms in Be stars.

Contribution

It provides the first detailed analysis of pulsation frequencies in HD 50209, linking observed gravity modes to stellar rotation and physical parameters.

Findings

Detected four gravity-mode frequencies with azimuthal orders m=0,-1,-2,-3

Identified a rotational period of approximately 7.75 microHz

Confirmed pulsations consistent with the star's position near the SPB instability strip

Abstract

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. To contribute to this discussion, we analyse the photometric time series of the B8IVe star HD 50209 observed by the CoRoT mission in the seismology field. 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. We have found four frequencies which correspond to gravity modes with azimuthal order m=0,-1,-2,-3 with the same pulsational frequency in the co-rotating frame. We also found a rotational period with a frequency of 0.679 \cd (7.754 $\mu$Hz). HD 50209 is a pulsating Be star as expected from its position in the HR diagram, close to the SPB instability strip.