Cylindrical and spherical pistons as drivers of MHD shocks (CROSBI ID 644270)
Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija
Podaci o odgovornosti
Žic, Tomislav ; Vršnak, Bojan ; Temmer, Manuela
engleski
Cylindrical and spherical pistons as drivers of MHD shocks
We consider expanding cylindrical and spherical structures as drivers of MHD shock waves. It is assumed that the source surface accelerates over a certain time interval to achieve a particular maximum velocity. Such an expansion creates a large amplitude simple wave in the ambient plasma. Due to the nonlinear evolution of the wave front, its profile steepens and after a certain time/distance a discontinuity forms, marking the onset of the shock formation. We investigate how the time/distance needed for the shock formation depends on various input parameters: the acceleration phase duration, maximum expansion velocity (defining also acceleration), Alfvén velocity (defining also Mach number), initial size of the piston. The model is an extension of the 1- dimensional model by Vršnak and Lulić [2000] ; the basic difference lies in the fact that in the 3D evolution, a decrease of the wave amplitude with distance must be taken into account. We present basic results, focusing on the timing of the shock formation in the low versus high plasma beta environment. Implications for the coronal conditions are discussed.
Shock waves ; magnetohydrodynamics (MHD) ; Sun: corona ; Sun: coronal mass ejections (CMEs) ; Sun: flares
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Podaci o prilogu
2007.
objavljeno
Podaci o matičnoj publikaciji
Podaci o skupu
CESRA Workshop on "Solar Radio Physics and the Flare-CME Relationship"
predavanje
12.06.2007-16.06.2007
Janjina, Grčka