From eruption to post-flare rain: a 2.5D MHD model

TL;DR

This study uses advanced 2.5D MHD simulations to investigate the formation, eruption of magnetic flux ropes, and subsequent coronal rain in post-flare loops, providing insights into solar eruptive phenomena and coronal heating.

Contribution

It presents a detailed resistive-MHD simulation capturing flux rope eruptions and coronal rain formation, advancing understanding of solar flare dynamics and thermodynamics.

Findings

Multiple flux ropes can erupt spontaneously due to magnetic reconnection.

Thermal imbalance leads to catastrophic cooling and condensations.

Simulated coronal rain properties match observational data.

Abstract

The formation of the MFRs in the pre-flare stage, and how this leads to coronal rain in a post-eruption magnetic loop is not fully understood. We explore the formation, and eruption of MFRs, followed by the appearance of coronal rain in the post-flare loops, to understand the magnetic and thermodynamic properties of eruptive events and their multi-thermal aspects in the solar atmosphere. We perform a resistive-magnetohydrodynamic (MHD) simulation with the open-source code \texttt{MPI-AMRVAC} to explore the evolution of sheared magnetic arcades that can lead to flux rope eruptions. The system is in mechanical imbalance at the initial state, and evolves self-consistently in a non-adiabatic atmosphere under the influence of radiative losses, thermal conduction, and background heating. We use an additional level of adaptive mesh refinement to achieve the smallest cell size of $\approx 32.7$ km in each direction to reveal the fine structures in the system. The system achieves a semi-equilibrium state after a short transient evolution from its initial mechanically imbalanced condition. A series of erupting MFRs is formed due to spontaneous magnetic reconnection, across current sheets created underneath the erupting flux ropes. Gradual development of thermal imbalance is noticed at a loop top in the post-eruption phase, which leads to catastrophic cooling and formation of condensations. We obtain plasma blobs which fall down along the magnetic loop in the form of coronal rain. The dynamical and thermodynamic properties of these cool-condensations are in good agreement with observations of post-flare coronal rain. The presented simulation supports the development and eruption of multiple MFRs, and the formation of coronal rain in post-flare loops, which is one of the key aspects to reveal the coronal heating mystery in the solar atmosphere.