How to estimate invisible free magnetic energy stored in a solar emerging flux region

Abstract:

We report how to estimate invisible free magnetic energy in a solar emerging flux region, which is a key to understanding the energetics of solar active phenomena such as solar flares and coronal mass ejections. By performing 3-dimensional magnetohydrodynamic simulations, we derived power-law relationships among emerged magnetic flux, free magnetic energy and relative magnetic helicity in several simulated emerging flux regions. We then discuss a difference between apparent magnetic flux and net magnetic flux. Since emerged magnetic flux is one of the possible observed quantities on the Sun, these relationships may give a way to estimate invisible free magnetic energy stored in a solar active region.