Validation of the magnetic energy vs. helicity scaling in solar magnetic structures

Abstract

We assess the validity of the free magnetic energy - relative magnetic helicity diagram for solar magnetic structures. We used two different methods of calculating the free magnetic energy and the relative magnetic helicity budgets: a classical, volume-calculation nonlinear force-free (NLFF) method applied to finite coronal magnetic structures and a surface-calculation NLFF derivation that relies on a single photospheric or chromospheric vector magnetogram. Both methods were applied to two different data sets, namely synthetic active-region cases obtained by three-dimensional magneto-hydrodynamic (MHD) simulations and observed active-region cases, which include both eruptive and noneruptive magnetic structures. The derived energy--helicity diagram shows a consistent monotonic scaling between relative helicity and free energy with a scaling index 0.84$\pm$0.05 for both data sets and calculation methods. It also confirms the segregation between noneruptive and eruptive active regions and the existence of thresholds in both free energy and relative helicity for active regions to enter eruptive territory. We consider the previously reported energy-helicity diagram of solar magnetic structures as adequately validated and envision a significant role of the uncovered scaling in future studies of solar magnetism.

References in corpus (5)

• Optimization code with weighting function for the reconstruction of coronal magnetic fields
• Validation and Benchmarking of a Practical Free Magnetic Energy and Relative Magnetic Helicity Budget Calculation in Solar Magnetic Structures
• The dependence of the helicity bound of force-free magnetic fields on boundary conditions
• Recurrent explosive eruptions and the sigmoid-to-arcade transformation in the sun driven by dynamical magnetic flux emergence
• Energy and helicity budgets of solar quiet regions

Cited by in corpus (4)

• Flare-productive active regions
• Prominence and Filament Eruptions Observed by the Solar Dynamics Observatory: Statistical Properties, Kinematics, and Online Catalog
• Magnetic helicity estimations in models and observations of the solar magnetic field. Part I: Finite volume methods
• Calculations for the Practical Applications of Quadratic Helicity in MHD