The 17 February 2013 sunquake in the context of the active region's magnetic field configuration

TL;DR

This study combines multi-layer solar observations with magnetic field modeling to understand how magnetic configurations and flux rope destabilization in active region 11675 led to a sunquake, highlighting the role of magnetic lensing.

Contribution

It introduces a novel approach by integrating observational data with a non-linear force-free magnetic field model to analyze sunquake initiation mechanisms.

Findings

Sunquake linked to flux rope destabilization and M-class flare.

Photospheric motions from flux emergence modified the magnetic environment.

Magnetic lensing by surrounding field lines may focus energy to trigger the sunquake.

Abstract

Sunquakes are created by the hydrodynamic response of the lower atmosphere to a sudden deposition of energy and momentum. In this study we investigate a sunquake that occurred in NOAA active region 11675 on 17 February 2013. Observations of the corona, chromosphere and photosphere are brought together for the first time with a non-linear force-free model of the active region's magnetic field in order to probe the magnetic environment in which the sunquake was initiated. We find that the sunquake was associated with the destabilization of a flux rope and an associated M-class GOES flare. Active region 11675 was in its emergence phase at the time of the sunquake and photospheric motions caused by the emergence heavily modified the flux rope and its associated quasi-separatrix layers, eventually triggering the flux rope's instability. The flux rope was surrounded by an extended envelope of field lines rooted in a small area at the approximate position of the sunquake. We argue that the configuration of the envelope, by interacting with the expanding flux rope, created a "magnetic lens" that may have focussed energy in one particular location the photosphere, creating the necessary conditions for the initiation of the sunquake.