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Multi-thermal jet formation triggered by flux emergence
Flux emergence is responsible for various solar eruptions. Combining
observation and simulations, we investigate the influence of flux emergence at
one footpoint of an arcade on coronal rain as well as induced eruptions. The
emergence changes the pressure in the loops, and the internal coronal rain all
moves to the other side. The emerging flux reconnects with the overlying
magnetic field, forming a current sheet and magnetic islands. The plasma is
ejected outwards and heated, forming a cool jet ~ 6000 K and a hot X-ray jet ~
4 MK simultaneously. The jet dynamical properties agree very well between
observation and simulation. In the simulation, the jet also displays transverse
oscillations with a period of 8 minutes, a so-called whip-like motion. The
movement of the jet and dense plasmoids changes the configuration of the local
magnetic field, facilitating the occurrence of Kelvin--Helmholtz instability,
and vortex-like structures form at the boundary of the jet. Our simulation
clearly demonstrates the effect of emergence on coronal rain, the dynamical
details of reconnecting plasmoid chains, the formation of multi-thermal jets,
and the cycling of cool mass between the chromosphere and the corona.Comment: 11 pages, 5 figures, accepted for publication in The Astrophysical
Journal Letter
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