Thermodynamics of the Solar Corona and Evolution of the Solar Magnetic Field as Inferred from the total Solar Eclipse Observations of 2010 July 11
Publication date: 07 June 2011
Authors: Shadia Rifai Habbal et al
Journal: The Astrophysical Journal
Volume: 734
Issue: 2
Page: 120
Year: 2011
Copyright: IOP Publishing Ltd.
We report on the first multi-wavelength coronal observations, taken simultaneously in white light, H alpha 656.3 nm, Fe IX 435.9 nm, Fe X 637.4 nm, Fe XI 789.2 nm, Fe XIII 1074.7 nm, Fe XIV 530.3 nm, and Ni XV 670.2 nm, during the total solar eclipse of 2010 July 11 from the atoll of Tatakoto in French Polynesia. The data enabled temperature differentiations as low as 0.2 × 10^6 K. The first-ever images of the corona in Fe IX and Ni XV showed that there was very little plasma below 5 × 10^5 K and above 2.5 × 10^6 K. The suite of multi-wavelength observations also showed that open field lines have an electron temperature near 1× 10^6 K, while the hottest, 2× 10^6 K, plasma resides in intricate loops forming the bulges of streamers, also known as cavities, as discovered in our previous eclipse observations. The eclipse images also revealed unusual coronal structures, in the form of ripples and streaks, produced by the passage of coronal mass ejections and eruptive prominences prior to totality, which could be identified with distinct temperatures for the first time. These trails were most prominent at 106 K. Simultaneous Fe X 17.4 nm observations from Proba2/SWAP provided the first opportunity to compare Fe X emission at 637.4 nm with its extreme-ultraviolet (EUV) counterpart. This comparison demonstrated the unique diagnostic capabilities of the coronal forbidden lines for exploring the evolution of the coronal magnetic field and the thermodynamics of the coronal plasma, in comparison with their EUV counterparts in the distance range of 1-3 solar radii. These diagnostics are currently missing from present space-borne and ground-based observatories.
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