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Quantification of Bursty and Steady Heating of the 4-8 MK Coronal Plasma in a Solar Active Region using Maps of Minimum, Maximum, and Average Brightness

Presentation #406.01 in the session Coronal Heating Observational Constraints.

Published onSep 18, 2023
Quantification of Bursty and Steady Heating of the 4-8 MK Coronal Plasma in a Solar Active Region using Maps of Minimum, Maximum, and Average Brightness

We present a method of quantifying coronal heating’s bursty and steady components, applying it to \FeXVIII\ (hot94) emission of an active region (AR) observed by SDO/AIA. The maximum, minimum, and average brightness values for each pixel, over a 24 hour period, yield a maximum-brightness map, a minimum-brightness map, and an average-brightness map of the AR. Running sets of such three maps come from repeating this process for each time step of running windows of 20, 16, 12, 8, 5, 3, 1 and 0.5 hours. From each running window’s set of three maps, we obtain the AR’s three corresponding luminosity light curves. We find that the time-averaged ratio of minimum-brightness-map luminosity to average-brightness-map luminosity increases as the time window decreases, and the time-averaged ratio of maximum-brightness-map luminosity to average-brightness-map luminosity decreases as the window decreases. For the 24-hour window, the minimum-brightness map’s luminosity is 5% of the average-brightness map’s luminosity, indicating that at most 5% of the AR’s hot94 luminosity is from heating that is steady for 24 hours. This upper limit on the fraction of the hot94 luminosity from steady heating increases to 33% for the 30-minute running window. This suggests that the heating of the 4-8 MK plasma in this AR is mostly in bursts lasting less than 30 minutes. At most a third of the heating is steady for 30 minutes.

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