RUI: Coronal Plasma Observed at Eclipses and Otherwise Simultaneously

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Solar eclipses are of widespread public interest in the countries from which they are visible, and they therefore provide an important opportunity for public education about astronomy as well as for efforts on spreading information domestically on safe solar observing. The PI was Chair of the International Astronomical Union's Working Group on Eclipses and liaison to the American Astronomical Society's Eclipse Task Force for the 2017 Great American Eclipse, and for the upcoming 2024 eclipse. Studies of the solar corona at eclipses have been a major part of the success of the Williams College department in attracting and training students. Undergraduate students, increasingly including members of underrepresented groups through Williams's need-blind admissions policy, have been intimately connected with the eclipse expeditions and the associated data reduction and analysis; this project enables the active involvement and training of students to continue. Specifically, this proposal is to perform high resolution optical observations, rapid imaging of the corona, and radio and spectroscopic measurements. The project will include comparisons with other space and ground based observations as well as comparisons with state of the art computer models. This particular project is to take advantage of the data from the 2017 total solar eclipse and to observe the 2019 and 2020 total eclipses. The focus of the project is on observing the white-light corona and working with highly processed images that bring out detail and extreme contrast. This will allow improved measurements of dynamics of coronal plumes and other coronal features, especially coronal mass ejections. Additionally, filtergrams and spectra of the green-line (Fe XIV) and red-line (Fe X) coronas will be used to examine the contrast of regions of different temperatures. The proposed observations include exquisitely high-resolution observations with Lyot/Halle filters. The team will also complete the analysis of high-frequency (1 Hz) power spectra of coronal loops to compare mechanisms of coronal heating and carry out similar observations at the 2020 eclipse. Spectrographic observations are important as the spectral-line ratios continue to change over the solar-activity cycle, which now past a low maximum and passing through minimum. The team will also complete 2017 eclipse analysis with data from radio telescopes, including the Jansky Very Large Array, which is providing the best-ever mapping of active regions to pinpoint the different locations of radio and EUV eruption origins, and use an Argentian radiotelescope in 2019 and 2020.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.