Speaker
Leonid L. Kitchatinov
(Institute for Solar-Terrestrial Physics, Irkutsk)
Description
Instabilities in stellar radiation zones are important for angular momentum
transport, mixing of chemical species and, possibly, for dynamos. It is shown that
even a very small radial differential rotation can lead to instability. Surfaces of
constant density and constant pressure do not coincide in differentially rotating
stars. The baroclinicity of stratification results in a hydrodynamical instability.
The instability modes global in horizontal dimensions but short-scaled in radius are
computed. Two families of unstable disturbances are identified leading to the
interpretation of the instability as a stability loss to excitation of g- and r-modes
of global oscillations. Decreasing thermal conductivity produces a destabilizing
effect. Unstable disturbances are helical. The instability is, therefore, prone to
dynamos. The sign of kinetic helicity depends on the sense of radial differential
rotation.
Primary author
Leonid L. Kitchatinov
(Institute for Solar-Terrestrial Physics, Irkutsk)
