Evolution and Distribution of Current Helicity in Full-Sun Simulations

TL;DR

This study uses global-scale simulations to analyze the evolution and distribution of current helicity in the solar atmosphere, revealing patterns consistent with observations and highlighting the complexity of magnetic structures.

Contribution

The paper presents a novel simulation approach that reproduces the observed hemispheric pattern of current helicity distribution over multiple solar rotations.

Findings

Latitudinal distribution of current helicity matches observed hemispheric sign patterns.

Significant scatter and intermixing of helicity signs are observed, aligning with real data.

Local current helicity densities exceed predictions from linear force-free models.

Abstract

Current helicity quantifies the location of twisted and sheared non-potential structures in a magnetic field. We simulate the evolution of magnetic fields in the solar atmosphere in response to flux emergence and shearing by photospheric motions. In our global-scale simulation over many solar rotations the latitudinal distribution of current helicity develops a clear statistical pattern, matching the observed hemispheric sign at active latitudes. In agreement with observations there is significant scatter and intermixing of both signs of helicity, where we find local values of current helicity density that are much higher than those predicted by linear force-free extrapolations. Forthcoming full-disk vector magnetograms from Solar Dynamics Observatory will provide an ideal opportunity to test our theoretical results on the evolution and distribution of current helicity, both globally and in single active regions.