Coronal response to magnetically-suppressed CME events in M-dwarf stars

TL;DR

This study uses advanced simulations to explore how CMEs in M-dwarf stars cause observable coronal responses, revealing flare-like signatures, plasma flows, and dimming effects, with implications for future X-ray observations.

Contribution

First detailed numerical simulations of CMEs in realistic magnetic fields of M-dwarf stars, uncovering novel observable coronal responses and dynamics.

Findings

CME eruptions induce flare-like signatures in coronal emission.

Fragmentation and flow patterns resemble solar coronal rain.

Coronal dimming occurs during CME events, similar to solar phenomena.

Abstract

We report the results of the first state-of-the-art numerical simulations of Coronal Mass Ejections (CMEs) taking place in realistic magnetic field configurations of moderately active M-dwarf stars. Our analysis indicates that a clear, novel, and observable, coronal response is generated due to the collapse of the eruption and its eventual release into the stellar wind. Escaping CME events, weakly suppressed by the large-scale field, induce a flare-like signature in the emission from coronal material at different temperatures due to compression and associated heating. Such flare-like profiles display a distinctive temporal evolution in their Doppler shift signal (from red to blue), as the eruption first collapses towards the star and then perturbs the ambient magnetized plasma on its way outwards. For stellar fields providing partial confinement, CME fragmentation takes place, leading to rise and fall flow patterns which resemble the solar coronal rain cycle. In strongly suppressed events, the response is better described as a gradual brightening, in which the failed CME is deposited in the form of a coronal rain cloud leading to a much slower rise in the ambient high-energy flux by relatively small factors ($\sim2-3$). In all the considered cases (escaping/confined) a fractional decrease in the emission from mid-range coronal temperature plasma occurs, similar to the coronal dimming events observed on the Sun. Detection of the observational signatures of these CME-induced features requires a sensitive next generation X-ray space telescope.