Steve Balbus
Laboratoire Radioastronomie, Ecole Normale Sup. (ENS) (Paris, France)
Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris
|
| « A simple approach to the solar rotation profile magnetism, marginal stability, and a thermal wind » |
|
Steve Balbus |
|
Since its discovery by helioiseismology in the 1980's, the striking pattern of solar differential rotation in the sun's outer convective layers has defied both theoretical explanation and reproduction in large scale numerical simulations. In this talk, I will present arguments as to how and why the observed rotation profile in the sun is a direct consequence of the (inevitable) presence of weak magnetic fields. The combination of helioseismology data and straightforward weak field magnetohydrodynamics field produces a marginally unstable convective layer, precisely as required. The theory makes detailed predictions for the nature of the convective transport as well as the internal solar magnetic field structure. Moreover, the solar isorotation contours may also be determined analytically, and the self-consistent agreement with the helioseismology data is very good. (The theory does not apply to the solar tachocline, which involves very different dynamics.) This ``magnetobaroclinic" theory of solar rotation is itself subject to strict numerical verification at currently accessible numerical resolution.
|
|
vendredi 27 mars 2009 - 11:00 Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |