Sunquake Generation by Coronal Magnetic Restructuring

TL;DR

This study proposes a new mechanism for sunquake generation driven by magnetic field restructuring during solar flares and CMEs, supported by MHD simulations showing acoustic wave production.

Contribution

It introduces a novel explanation involving Alfven-sound resonance and ponderomotive force, linking magnetic tilt changes to sunquake initiation.

Findings

Acoustic waves are generated when magnetic tilt changes by about 10 degrees.

Stronger coronal magnetic fields produce more energetic sunquakes.

Magnetic field strength and tilt change timescales influence sunquake energy.

Abstract

Sunquakes are the surface signatures of acoustic waves in the Sun's interior that are produced by some but not all flares and coronal mass ejections (CMEs). This paper explores a mechanism for sunquake generation by the magnetic field changes that occur during flares and CMEs, using MHD simulations with a semiempirical FAL-C atmosphere to demonstrate the generation of acoustic waves in the interior in response to changing magnetic tilt in the corona. We find that Alfven-sound resonance combined with the ponderomotive force produces acoustic waves in the interior with sufficient energy to match sunquake observations when the magnetic field angle changes by the order of 10 degrees in a region where the coronal field strength is a few hundred gauss or more. The most energetic sunquakes are produced when the coronal field is strong, while the variation of magnetic field strength with height and the time scale of the tilt change are of secondary importance.