Multi-thermal dynamics and energetics of a coronal mass ejection in the low solar atmosphere

Abstract

The aim of this work is to determine the multi-thermal characteristics and plasma energetics of an eruptive plasmoid and occulted flare observed by Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA). We study an event from 03-Nov-2010 (peaking at 12:20UT in GOES soft X-rays) of a coronal mass ejection and occulted flare which demonstrates the morphology of a classic erupting flux rope. The high spatial, and time resolution, and six coronal channels, of the SDO/AIA images allows the dynamics of the multi-thermal emission during the initial phases of eruption to be studied in detail. The Differential Emission Measure (DEM) is calculated, using an optimised version of a regularized inversion method (Hannah & Kontar 2012), for each pixel across the six channels at different times, resulting in emission measure maps and movies in a variety of temperature ranges. We find that the core of the erupting plasmoid is hot (8-11, 11-14MK) with a similarly hot filamentary "stem" structure connecting it to the lower atmosphere, which could be interpreted as the current sheet in the flux rope model, though is wider than these models suggest. The velocity of the leading edge of the eruption is 597-664 km s$^{-1}$ in the temperature range $\ge$3-4MK and between 1029-1246 km s$^{-1}$ for $\le$2-3MK. We estimate the density (in 11-14 MK) of the erupting core and stem during the impulsive phase to be about $3\times10^9$ cm$^{-3}$, $6\times10^9$ cm$^{-3}$, $9\times10^8$ cm$^{-3}$ in the plasmoid core, stem and surrounding envelope of material. This gives thermal energy estimates of $5\times10^{29}$ erg, $1\times10^{29}$ erg and $2\times10^{30}$ erg. The kinetic energy for the core and envelope is slightly smaller. The thermal energy of the core and current sheet grows during the eruption, suggesting continuous influx of energy presumably via reconnection.