HgMn stars are chemically peculiar stars that happen to be very stable stars. There is as of yet no evidence for pulsations and only disputed evidence for rotational variability. Why then are these stars interesting in the context of asteroseismology?
As slowly rotating chemically peculiar stars, it is expected that diffusion and chemical separation is very efficient in these stars. In recent years, evidence for a strong enhancement of the metal opacity peak in such stars has been uncovered. As a result the contribution of the metals to the excitation of pulsations is enhanced compared to chemically normal stars.
The hotter HgMn stars overlap the distribution of the cooler SPB stars in the HR diagram. It is now well known that pulsations in SPB stars are driven by the metals' opacity and that they are variable at the solar composition. The questions then arise: Are HgMn really stable? If so, why would they be? Which processes would prevent the excitation of pulsations? If they are variable, why are the amplitudes so small? The answers to these questions have should lead to a much greater understanding of stellar dynamics in B stars that could otherwise remain hidden.
This presentation will present models of HgMn stars, analyze their stability, and discuss the issues regarding internal dynamics, mixing mechanisms, and mass loss in these stars. We will present what we expect to learn from the seismological study of HgMn stars.

 
Print this abstract