Events in Physics

In flare-relevant current sheets, tearing instability can trigger explosive magnetic reconnection and plasmoid formation, while thermal instabilities can lead to condensation phenomena such as the formation of prominences and coronal rain in the solar atmosphere.

In the first part of my talk, I will discuss how thermal and tearing modes can reinforce each other, driving the fragmentation of a 2D current sheet in the solar corona through an explosive reconnection process. This process is characterized by the formation of plasmoids that interact and trap condensing plasma. In 3D coupled tearing-thermal modeling, I will showcase the formation of flux ropes and cool condensations in their vicinity. I will also demonstrate how the coalescence of two flux ropes in a 2.5D stratified solar atmosphere leads to small-scale, short-lived, and collimated outflows with nanoflare energy range, sharing similarities with the properties of recently discovered reconnection ‘nanojets’. Furthermore, I will present synthetic counterparts (imaging and line profiles) of the simulation(s), which are compatible with existing (SDO/AIA, GONG) and upcoming (MUSE, EUVST) telescopes, and compare the synthetic observables with an existing observation of nanojets.

In the second part of my talk, I will discuss a 2.5D MHD model of post-flare coronal rain, where a series of erupting flux ropes forms due to spontaneous magnetic reconnection across current sheets. I will show how the persistence and spatial distribution of magnetic shear along the arcades play a decisive role in determining the onset and evolution of flux rope instabilities. Finally, I will highlight how a gradual development of thermal imbalance at the loop top during the post-eruption phase leads to a catastrophic cooling and the subsequent formation of coronal rain.