Dynamics and Thermodynamics of the Corona Observed During the Total Solar Eclipse of 20 March 2015

Abstract:

Total solar eclipse observations are snapshots of the instantaneous dynamic state of the corona, and each observation never fails to yield surprises. Occurring at the declining phase of solar cycle 24, the 20 March 2015 total solar eclipse was no exception. Images taken through narrow bandpass filters centered on the Fe XIV 530.3 nm and Fe XI 789.2 nm coronal emission lines, showed a corona dominated by strong Fe XIV emission, with a peak ionization temperature of 1.8 MK, and with weak Fe XI emission at 1.1 MK, present mostly over the two poles. Simultaneous imaging spectroscopy through a dual channel high-resolution spectrometer, centered on these two wavelengths, revealed Doppler red shifts exceeding 1000 km/s in the extended corona, covering a distance range of up to 1.5 solar radii above the solar surface. These redshifts together with the observed Doppler broadening could be assigned to specific coronal structures, which were observed simultaneously in high resolution white light images. By comparing these observations with contemporaneous observations from SDO, SWAP/Proba2 and LASCO/C2 and C3, the dynamics of the coronal plasma, as well as its thermodynamics, could be mapped in a region of space, untenable to present-day observatories. These latest eclipse observations underscore the unique scientific opportunities accessible with similar instrumentation during the all-american 21 August 2017 total solar eclipse.