Talk abstract details

Rapidly oscillating Ap stars exhibit an astrophysically
interesting combination of strong, dipolar-like magnetic fields
and high-overtone p-mode pulsations similar to the Sun. To
understand the pulsations of these magnetic stars, we have carried
out 2-D time-dependent, non-linear magneto-hydrodynamical
simulations of waves for a realistic atmospheric stratification of
a cool Ap star. We explore a grid of simulations in a wide
parameter space, treating oscillations of the velocity, magnetic
field and thermodynamic quantities in a self-consistent manner. In
this contribution, we report a detailed study of the influence of
the atmosphere and the magnetic field on the propagation and
reflection properties of different magneto-acoustic modes,
formation of node surfaces, and relative variation of different
quantities. We show how these properties depend on the relative
location of three important layers: cut-off layer, mode
transformation layer and the density inversion layer at the
photospheric base. Our simulations reproduce all main features of
the observed pulsational behavior of roAp stars.