β CEP STARS AS (ASTEROSEISMO)LOGICAL TARGETS FOR EDDINGTON

摘要

Asteroseismological studies of β Cep stars have many astrophysical applications. With the detailed insights into the structure of these objects that can be obtained, questions such as the presence and amount of differential interior rotation, the amount of convective core overshooting, the interior magnetic field structure or the iron abundance in the driving region can be addressed. Stellar evolutionary computations can be calibrated from the ZAMS to the supernova explosion. Guided by two case studies, v Eridani and HD 129929, we review the present status of asteroseismology of β Cep stars and show that the first intriguing results are already being obtained. Further rapid progress is limited by the accuracy of ground-based observations. Observations from space, such as Eddington will obtain, are bound to deepen our understanding even further. We address the possible problem of mode crowding that could spoil the results from space-based observations with short time baselines, but show that mode trapping and geometrical cancellation may provide natural mode selection mechanisms that make mode crowding effects less severe. We also demonstrate that colour information in the Eddington data will allow efficient mode discrimination and is therefore desirable. The new pulsation modes of intermediate spherical degree l we expect to detect, resolve and identify with Eddington, will be sufficient to map the whole interior of β Cep stars in great detail, starting yet another new era of precision asteroseismology. β Cep stars are therefore logical targets for the Eddington mission.