Abstract
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. 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.
Highlights
Solar filaments and prominences are observed to be a major precursor of coronal mass ejections (CMEs) (e.g., Webb and Hundhausen, 1987)
To examine the magnetic field that produces the substructure inside the EUV cavity, we have traced field lines that thread through the region that contributes to the EUV emission of the prominence “horns.” Figure 11 shows a set of such field lines, together with a cross section showing the local emission intensity in EUV 193 Å channel (the integrand ne2f193(T) in Equation 2), with the cross-section placed at different locations along the flux rope for the different panels (a–e), and without showing the cross-section in panel (f)
We have carried out MHD simulation of the quasi-static evolution and onset of eruption of a prominence-forming coronal flux rope under a coronal streamer, extending the previous work of F17 and F18
Summary
Solar filaments and prominences are observed to be a major precursor of coronal mass ejections (CMEs) (e.g., Webb and Hundhausen, 1987). Fan (2017) (hereafter F17) and Fan (2018) (hereafter F18) have carried out 3D MHD simulations of prominence forming coronal flux ropes under coronal streamers, with the flux rope evolving from quasi-equilibrium to onset of eruption, leading to a CME with associated prominence eruption. In those simulations, a significantly twisted, longitudinally extended flux rope is built up in the corona under a pre-existing coronal streamer solution by an imposed flux emergence at the lower boundary. We find that the flux rope begins to erupt at a significantly lower height, consistent with the onset of the torus instability, and results in a fast CME with an associated prominence eruption that shows a kinked morphology
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