Comparison of energies between eruptive phenomena and magnetic field in AR 10930

Abstract

We present a study comparing the energy carried away by a coronal mass ejection (CME) and the radiative energy loss in associated flare plasma, with the decrease in magnetic free energy during a release in active region NOAA 10930 on December 13, 2006 during the declining phase of the solar cycle 23. The ejected CME was fast and directed towards the Earth with a projected speed of ~1780 km s-1 and a de-projected speed of ~3060 km s-1. We regard these as lower and upper limits for our calculations. It was accompanied by an X3.4 class flare in the active region. The CME carried (1.2-4.5)X1032 erg (projected-deprojected) of kinetic and gravitational potential energy. The estimated radiative energy loss during the flare was found to be 9.04X1030 erg. The sum of these energies was compared with the decrease in measured free magnetic energy during the flare/CME. The free energy is that above the minimum energy configuration and was estimated using the magnetic virial theorem. The estimated decrease in magnetic free energy is large, 3.11X1032 erg after the flare/CME compared to the pre-flare energy. Given the range of possible energies we estimate that 50-100% of the CME energy arose from the active region. The rest of the free magnetic energy was distributed among the radiative energy loss, particle acceleration, plasma and magnetic field reorientation.