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Inferences of the Absolute Brightness of Fe X, XI and XIV, and the Electron Temperature from the 2019 Total Solar Eclipse

Presentation #303.05 in the session Solar and Atmospheric Science with Eclipses.

Published onOct 20, 2022
Inferences of the Absolute Brightness of Fe X, XI and XIV, and the Electron Temperature from the 2019 Total Solar Eclipse

We present the spatially resolved absolute brightness of Fe X, Fe XI and Fe XIV coronal emission lines observed during the 2019 July 2 total solar eclipse between 1.08 and 3.0 Rsun. The topology is that of a classic solar minimum corona, with a dipole field dominance showcased by large polar coronal holes and two wide equatorial streamer belts. The Fe XI line is found to be the brightest line followed by Fe X and Fe XIV (in disk Bsun units). All lines vary in brightness between streamers and coronal holes; while Fe XIV has the largest variation, Fe X remains rather uniform with latitude. The Fe line ratios are used to infer the relative ionic abundances and electron temperature (Te) throughout the corona, yielding values from 1.2 MK in coronal holes up to 1.7 MK in the core of streamers. The line brightnesses and inferred Te values are compared to the PSI Magnetohydrodynamic (MHD) model prediction of the eclipse. The MHD model predicts the Fe lines rather well in the coronal streamers but underestimates the brightness of the Fe lines in coronal holes. The MHD model generally underestimates the Te values, especially in polar open field regions, pointing to a slightly insufficient heating mechanism and/or limitations in the modeling approach.

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