Test of the capabilities of Doppler imaging technique for reconstruction of
the non-radial pulsation velocity field. The rectangular and spherical plots show amplitude
distribution for the vertical component of the pulsation velocity field due to the
l=6, m=4 mode recovered from the simulated data. No a priori assumptions
about functional form of the pulsational disturbances has been introduced.
A complete description of time-dependent pulsational
fluctuations requires imaging of two velocity amplitude maps (or, equivalently, reconstruction
of the surface variation of the pulsation amplitude and phase) for each vector component
of the velocity field. These two velocity amplitude maps are presented in the
left and right groups of panels.
Kochukhov, 2004, A&A, 423, 613
The first Doppler image of the stellar pulsation velocity field delivers
a solution of the long-standing problem of the pulsation geometry of magnetic peculiar
stars. These maps show the vertical
velocity component of non-radial pulsations in the roAp star HR 3831. Only one
amplitude map contains significant structures which is a signature of a nearly axisymmetric
pulsation. Pulsation axis is inclined by about 90o relative to the stellar
axis of rotation and is demonstrated to be aligned with the axis of the stellar magnetic field.
Pulsations are due to the dipole l=1 mode, distorted by the magnetic field in a way that
significant axisymmetric l=3 component appears and pulsation amplitude
is increased at the magnetic poles.
Kochukhov, 2004, ApJ, 615, L149