Collaborative Research: Citizen CATE Next-Generation 2024 Total Solar Eclipse Experiment, Phase 3

Despite well over 100 years of scientific observation, many fundamental questions about the nature of the solar corona remain unanswered. The corona is permeated by complex, highly structured and intense magnetic fields coupled to hot plasma at temperatures of 1–10 million Kelvin, over 100 times hotter than the underlying surface, the photosphere. The middle corona mediates almost all the outflow from the Sun to the heliosphere and hosts transitions between the physical regimes of the inner and outer coronae but remains poorly characterized due to the difficulty in observing the dim emission from this region. This project will (1) determine the connectivity of structures that span the middle corona; (2) measure the flow of the nascent solar wind; (3) identify and characterize magnetic reconnection; and (4) characterize polarization in prominences to derive physical parameters important for solar and stellar understanding. Through these investigations, this project will characterize the processes that shape the heating, structure, and evolution of the solar corona at scales that have not been previously studied in this way.

Total solar eclipses offer rare opportunities to study the solar corona without the inherent limitations of ground- or space-based coronagraphs, providing optimal conditions for ground-based observations that can achieve high resolution, high cadence, and wide field of view, with essentially zero stray light from the occulter (the Moon). The science objectives above are uniquely addressed by the one hour extended time series of high-sensitivity polarized coronal imaging obtained by CATE during the 2024 Total Solar Eclipse. The middle corona is difficult to study because it is often too faint for ground-based coronagraphs, and the required resolution is too fine for existing space-based instruments to trace its detailed connectivity. CATE 2024’s powerful polarization-sensitive eclipse observations permit 3D rendering and disambiguation of the fine structure previously observed by CATE 2017 and other projects, along with direct measurements of electron density. Eclipses also offer the best ground-based opportunity to detect scattered white-light emission from prominences, and the CATE 2024 data, combining both measurements of the linear polarization and a long duration, offer a new avenue to probe the prominence conditions, with a goal of being able to better interpret comparable observations of stellar prominences and coronal mass ejections.

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.

Award Number: 2511905
Principal Investigator: Cooper Downs
Funds Obligated: $69,882
State: CA