Thermal Evolution of the Plasma Sheet Region in the 2017 September 10 Solar Eruption

Abstract We conduct detailed thermal analysis of the plasma sheet region during the post-eruption phase of a flare that occurred on 2017 September 10, examining the thermal properties as both a function of space and time. The plasma sheet that develops is best observed using the 131 Å and 193 Å filters of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory. We use the differential emission measure technique to calculate the emission measure, emission measure weighted average temperature, density, and thermal energy inside the plasma sheet region. These quantities are calculated as a function time to assess how the conditions of the plasma sheet region change throughout the duration of the event. We find that there is a minimal decrease in the temperature as the plasma sheet region evolves. The total thermal energy in the plasma sheet is on the order of 1.5–3.0 10 29 erg for the first 1.5 hr of the eruption and then decreases. For the first time for this event, we examine the conductive and radiative loss rates, which indicate rapid cooling should be expected, contradicting the temperature results. These findings suggest that there are underlying mechanisms such as adiabatic heating and/or turbulence-induced suppression of conduction that contribute to the sustained hot conditions in the plasma sheet.