Simulating the Formation and Evolution of Solar Prominences in Coronal Cavities

Abstract:

The physical mechanism responsible for the formation and the mass cycling of
solar prominences has been uncertain for decades, because of the difficulty of
knowing the three-dimensional (3D) magnetic field hosting prominences and the mass
supply from chromosphere to prominences. Here we report comprehensive 3D
simulations which demonstrate that the chromospheric evaporation and the coronal
condensation in a magnetic flux rope lead to the formation of a quiescent
prominence with complex internal fluid dynamics. First, we simulate the formation
of a stable magnetic flux rope in the corona starting from a sheared magnetic
bipolar arcade driven by shearing and converging flows at the bottom, using
isothermal magnetohydrodynamics (MHD) modeling including gravity. Second, we
fill the magnetic flux rope with hydrostatic plasma from chromosphere to corona
and simulate a quiet sun in an equilibrium using full thermodynamic MHD
with anisotropic thermal conduction, optically thin radiative losses, and
parameterized heating. Then, we add extra strong heating localized in two
circular regions covering chromospheric foot points of the flux rope. As the
plasma is evaporated into corona, the lower part of the flux rope evolve into
thermally unstable situation due to dominative radiative losses, where multiple
blobs and threads of condensations form and move continuously mainly along local
magnetic field. Some of the condensations fall down to chromosphere without support
of magnetic dips near the foot region of the flux rope. Others linger in magnetic
dips and descend slowly. Synthetic images of Solar Dynamics Observatory views with
the Atmospheric Imaging Assembly shows many properties of quiescent prominences
from real observations, such as, dynamics dark threads under elliptical coronal
cavity.