Bounding the Energy of Solar Eruptions
Abstract
Major solar eruptions such as X-class flares and coronal mass ejections (CMEs) are the fundamental source of solar energetic particles and geomagnetic storms, and are thus key drivers of space weather at Earth. The energy for solar eruptions is recognized to originate in the solar magnetic field, and is believed to be stored as free magnetic energy (energy above the potential field state) prior to eruption. Solar active regions are the site of the most violent activity. Solar active regions can store widely varying amounts of energy, so knowledge of the free energy alone does not necessarily tell us when an eruption is imminent. For estimates of the free energy to provide predictive power, we must know how much energy a region can store - what is the energy bound?
In recent work, we have found that the energy of a particular field, the partially open field (POF), can place a useful bound on the energy of an eruption from real active regions, a much tighter constraint than the energy of the fully open field. However, in general, it is difficult to solve for the POF. In this presentation, we discuss methods for approximating the energy of this field, and show a comparison of the approximation for a case where the solution is known. We discuss the implications for understanding and predicting major solar eruptions. Research supported by NASA and AFOSR- Publication:
-
American Astronomical Society Meeting Abstracts #234
- Pub Date:
- June 2019
- Bibcode:
- 2019AAS...23431704L