RAPID: Multiwavelength Imaging and Spectroscopy of the Corona During the 2023 April 20 Total Solar Eclipse

Solar eclipses provide a rare opportunity to learn about the solar corona. This outer layer of the Sun is a mystery – it is millions of degrees and much hotter than the photosphere below it. This Rapid Response Research (RAPID) project will observe the 2023 April 20 total solar eclipse over Exmouth in Western Australia. The observations will observe coronal structures and will be compared with the High Altitude Observatory’s Upgraded Coronal Multi-Channel Polarimeter data and to in situ measurements from NASA’s Parker Solar Probe and Solar Orbiter. Team members will be actively engaged in outreach and graduate students will be trained in this research area. Total solar eclipses enable an uninterrupted spatial coverage of coronal structures from the solar surface out to several solar radii with coronal emission in the near ultraviolet, visible and near infrared, composed of radiatively excited emission lines, as well as continuum scattering by electrons and dust. Spectral line and continuum emission can yield the electron and ion temperature, density, ionic abundance, non-thermal motions and outflows of different coronal plasma constituents, hence valuable insights into the dynamics and thermodynamics of different manifestations of coronal heating processes. Ubiquitous sources of Fe 10+ emission at ∼ 1.2 MK throughout the corona are found to be invariably linked to 300 to 700 km/s in situ solar wind streams in observations spanning three solar cycles. These multiwavelength observations also unveil the role of prominence dynamics in driving plasma instabilities and CMEs, as well as releasing cool material embedded within CME fronts as they expand, in tandem, into interplanetary space. The proposed imaging and spectroscopic instrumentation for the 2023 April 20 total solar eclipse will enable the characterization of the thermodynamic properties of different ionic and neutral species during the rising activity phase of solar cycle 25. 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.