The Cause of Photospheric and Helioseismic Responses to Solar Flares: High-Energy Electrons or Protons?

TL;DR

This study investigates the causes of photospheric and helioseismic responses during a solar flare, finding that accelerated electrons, not protons, are more likely responsible for sunquakes, based on observational analysis.

Contribution

It provides observational evidence linking sunquake sources to high-energy electrons rather than protons during a solar flare.

Findings

Sunquakes are associated with electron sources, not proton sources.

Hydrodynamic responses form from multiple impulses of high-energy electrons.

Moving electron sources create anisotropic wave fronts in sunquakes.

Abstract

Analysis of the hydrodynamic and helioseismic effects in the photosphere during the solar flare of July 23, 2002, observed by Michelson Doppler Imager (MDI) on SOHO, and high-energy images from RHESSI shows that these effects are closely associated with sources of the hard X-ray emission, and that there are no such effects in the centroid region of the flare gamma-ray emission. These results demonstrate that contrary to expectations the hydrodynamic and helioseismic responses (''sunquakes") are more likely to be caused by accelerated electrons than by high-energy protons. A series of multiple impulses of high-energy electrons forms a hydrodynamic source moving in the photosphere with a supersonic speed. The moving source plays a critical role in the formation of the anisotropic wave front of sunquakes.