ECLIPSE2019: Direct measurement of the coronal magnetic field

Summary

Direct measurement of the coronal magnetic field remains a top priority for solar physics. The coronal magnetic field controls the structure, plasma dynamics, and stability of the solar atmosphere. Current efforts at detailed physics-based coronal modeling are limited by reliance on magnetic field boundary conditions at the surface of the Sun (the photosphere), where plasma conditions are dramatically different from the corona. The energy that maintains the coronal plasma and drives the solar wind and powers space weather is stored and released in the corona. The overall goal of the project is a more detailed understanding of magnetically sensitive lines in the 1.4 – 4 μm IR window. The PIs have identified several improvements to the AIR-Spec instrument that will result in an order of magnitude increase in the signal-to-noise ratio, enhanced image stability, and dramatically simpler operations. The 2017 AIR-Spec eclipse observations have demonstrated the capabilities of the NSF/NCAR HIAPER GV for targeted, time-critical solar observations, and AIR-Spec performed as expected. The PIs clearly detected five targeted coronal lines. The existence of a prominence allowed them to detect hydrogen Paschen, Brackett, and Pfund chromospheric lines. In addition, they have detected an unknown coronal IR line and show that the wavelength of the previously unobserved FeIX 2.845 μm line is significantly different from the calculated wavelength.