Simulation of dark lanes in post--flare supra--arcades, II. A contribution to the remote sensing of the coronal magnetic field

SCHULZ, W., COSTA, A., ELASKAR, S., CID, G.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2009 p. 1 - 10

0035-8711

ABSTRACTWe integrate the MHD ideal equations to simulate dark void sunwardly moving structures in post–flare supra–arcades. In Costa et al. (2009) we could numerically reproduce the observations described in Verwichte et al. (2005). We showed that the dark tracks are plasma vacuums generated by the bouncing and interfering of shocks and expansion waves, upstream an initial slow magnetoacoustic shock produced by a localized deposition of energy modeled as a pressure perturbation. The same pressure perturbation produces a transverse to thefield or perpendicular magnetic shock giving rise to nonlinear waves that compose the kink–like plasma void structures, with the same functional sunward decreasing phase speed and period’s constancy with height, as those determined by the observations. The numerical approach uses a finite-volume Harten-Yee TVD scheme to integrate the 1D 2 MHD equations specially designed to capture supersonic flow discontinuities. In this paper we accomplish a study of sensitivity to initial and background physical conditions of the phenomenon. Withthe aim of contributing to the remote sensing of the corona we describe the characteristics of different void structures in terms of physical conditions, i.e., magnetic field intensity and pressure perturbation, given a background density.