Scaling laws for magnetic flux, free magnetic energy, and relative magnetic helicity in emerging flux region


We investigated scaling laws for magnetic quantities in an emerging flux region, which could contribute to studying energetics of an active phenomenon observed in that region, such as a solar flare and coronal mass ejection. By performing a series of three-dimensional magnetohydrodynamic simulations with different degrees of field-line twist applied to an emerging flux tube, we obtained a set of emerging flux regions with different magnetic field configurations, and derived power-law relations between magnetic flux, free magnetic energy, and relative magnetic helicity in each of these emerging flux regions. Since the magnetic flux could be estimated via a surface integral of the magnetic field observed at a solar surface (photosphere), the scaling laws for the magnetic flux and the free magnetic energy/relative magnetic helicity could give a way to estimate the latter, which usually requires a volume integral of the magnetic field distributed in and above the photosphere.

This work was later developed into more general one.


Reference

Magara, T. 2014, PASJ, 66, L5




Back to the main page