Numerical Simulations of Solar Chromospheric Jets Associated with Emerging Flux

TL;DR

This study uses 2D MHD simulations to explore how magnetic reconnection and slow shock waves accelerate solar chromospheric jets, revealing new MHD effects in jet formation.

Contribution

It demonstrates the role of slow mode shock waves generated by magnetic reconnection in chromospheric jet acceleration, highlighting effects of reconnection height and new MHD interactions.

Findings

Slow mode shock waves are key in jet acceleration.

Reconnection near the photosphere causes upward-moving shocks.

Interaction between the transition region and shocks further accelerates plasma.

Abstract

We studied the acceleration mechanisms of chromospheric jets associated with emerging flux using a two dimensional magnetohydrodynamic (MHD) simulation. We found that slow mode shock waves generated by magnetic reconnection in the chromosphere and the photosphere play key roles in the acceleration mechanisms of chromospheric jets. An important parameter is the height of magnetic reconnection. When magnetic reconnection takes place near the photosphere, the reconnection out- flow collides with the region where the plasma beta is much larger than unity. Then the plasma moves along a magnetic field. This motion generates a slow mode wave. The slow mode wave develops to a strong slow shock as it propagates upward. When the slow shock crosses the transition region, the transition region is lifted up. As a result, we obtain a chromospheric jet as the lifted transition region. When magnetic reconnection takes place in the upper chromosphere, the chromospheric plasma is accelerated due to the combination of the Lorentz force and the whip-like motion of magnetic field. We found that the chromospheric plasma is further accelerated through the interaction between the transition region (steep density gradient) and a slow shock emanating from the reconnection point. This is an MHD effect which has not been discussed before.