MHD simulation of prominence-cavity system

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Thursday, May 9, 2019

We present magnetohydrodynamic simulation of the evolution from quasi-equilibrium to onset of eruption of a twisted, prominence-forming coronal magnetic flux rope underlying a corona streamer. The flux rope is built up by an imposed flux emergence at the lower boundary.

Images of 3D field lines
3D field lines (a), and synthetic SDO/AIA EUV images in 304 (b), 171 (c), 193 (d), and 211 (e) Angstrom channels, with the flux rope viewed nearly along its axis above the limb, at a time during the quasi-static phase. (f) shows the zoomed in view of the boxed area of (d). Panels (d), (e), and (f) show the formation of the prominence and the cavity surrounding it inside the helmet dome, with substructures inside the cavity including "U"–shaped or horn-liked features enclosing a central "cavity" on top of the prominence, in qualitative agreement with observations.

During the quasi-static phase of the evolution, we find the formation of a prominence-cavity system with qualitative features resembling observations, as shown by the synthetic SDO/AIA EUV images with the flux rope observed above the limb viewed nearly along its axis. The cavity contains substructures including "U"-shaped or horn-liked features extending from the prominence enclosing a central "cavity" on top of the prominence. The prominence condensations form in the dips of the highly twisted field lines due to runaway radiative cooling and the cavity is formed by the density depleted portions of the prominence-carrying field lines extending up from the dips. The prominence "horns" are threaded by twisted field lines containing shallow dips, where the prominence condensations have evaporated to coronal temperatures. The central "cavity" enclosed by the horns is found to correspond to a central hot and dense core containing twisted field lines that do not have dips. The flux rope eventually erupts as its central part rises quasi-statically to a critical height consistent with the onset of the torus instability. The erupting flux rope accelerates to a fast speed of nearly 900 km/s and the associated prominence eruption shows significant rotational motion and a kinked morphology.

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Publication Name: Frontiers in Astronomy and Space Sciences, section Stellar and Solar Physics
First HAO Author's Name: Yuhong Fan