Modelling results for two late Be stars observed by CoRoT

Abstract

AbstractThe Be stars HD 181231 (B5IVe) and HD 175869 (B8IIIe) have recently been observed using the CoRoT satellite for ∼5 months and ∼27 days respectively. This continuous, space‐based observation has allowed for the detection of many low amplitude modes in these stars. In the case of HD181231, the combination of the CoRoT data and ground‐based spectroscopic follow‐up data have placed tight constraints on the fundamental and pulsational properties of the star, allowing for detailed seismic modelling. For HD 175869, the variability has been proposed to be the result of inhomogeneities produced by stellar activity, located in or just above the photosphere. However, the CoRoT data does not exclude non‐radial pulsations as the origin of the variability. Through seismic modelling, we hope to clarify the origins of the variability. We compare observed frequencies to those calculated using a 2D stellar evolution and a 2D linear adiabatic pulsation code. We match the observed frequencies to a grid of 2D models in order to constrain the mass, age, rotation velocity and amount of convective core overshoot. We also compare our results to frequencies calculated using a 1D non‐adiabatic pulsation code. Using a combination of frequencies, we have been able to constrain the rotation and extra mixing for stars of a known mass and age. Here we determine the best fitting mass, age, rotation velocity and amount of extra mixing for these Be stars (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)