Stuttgart 2012 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 16: Astrophysik I
EP 16.7: Talk
Thursday, March 15, 2012, 12:00–12:15, V55.21
Rossby waves and polar spots in rapidly rotating stars: Implications for stellar wind evolution — •Teimuraz Zaqarashvili1, Ramon Oliver2, Jose Luis Ballester2, Marc Carbonell2, Maxim Khodachenko1, Helmut Lammer1, Martin Leitzinger3, and Petra Odert3 — 1Space Research Institute, Austria — 2University of Balearic Islands, Spain — 3University of Graz, Austria
We use shallow water magnetohydrodynamic equations to study the dynamics of large-scale waves at the rapidly rotating stellar tachoclines in the presence of toroidal magnetic field. Dispersion relations and latitudinal distribution of wave modes are derived. We found that low frequency magnetic Rossby waves tend to locate at poles. Unstable magnetic Rossby waves may lead to the local enhancement of magnetic flux at high latitudes of tachoclines in rapidly rotating stars. The enhanced magnetic flux may rise upwards due to the magnetic buoyancy in the form of tubes and appear as starspots at polar regions. The results may explain observed short period oscillations in magnetic activity and polar appearance of starspots in rapidly rotating stars. The polar spots may have important implications for the evolution of the stellar wind in young Sun-like stars.