New Coronal Science from NASA WB-57F High-Altitude Aircraft Observations of the 2017 Total Solar Eclipse
Abstract
Total solar eclipses present rare opportunities to study the complex solar corona, down to altitudes of just a few percent of a solar radius above the surface, using ground-based and airborne observatories that would otherwise be dominated by the intense solar disk and high sky brightness. Studying the corona is critical to gaining a better understanding of physical processes that occur on other stars and astrophysical objects, as well as understanding the dominant driver of space weather that affects human assets at Earth and elsewhere. For example, it is still poorly understood how the corona is heated to temperatures of 1-2 MK globally and up to 5-10 MK above active regions, while the underlying chromosphere is 100 times cooler; numerous theories abound, but are difficult to constrain due to the limited sensitivities and cadences of prior measurements. The stability of large-scale coronal structures and the extent of their reach to the middle and outer corona are also not well known, limited in large part by sensitivities and fields of view of existing observations.Airborne observations during a total eclipse provide unique advantages. By flying in the stratosphere at altitudes of 50 kft or higher, they avoid all weather, the seeing quality is enormously improved, and additional wavelengths such as near-IR also become available due to significantly reduced water absorption. An airborne observatory can also follow the Moon's shadow, increasing the total observing time by 50% or more.We present current results of solar coronal measurements from airborne observations of the 2017 Great American Total Solar Eclipse using two of NASA's WB-57 high-altitude research aircraft, each equipped with two 8.7" telescopes feeding high-sensitivity visible (green line and nearby continuum) and medium-wave IR (3-5 {μ}m) cameras operating at high cadence (30 Hz) with ∼3 arcsec/pixel platescale and ±3 R_{sun} fields of view. The aircraft flew along the eclipse path, separated by ∼110 km, to observe a summed ∼7.5 minutes of totality in both visible and MWIR. These observations enable groundbreaking studies of high-speed coherent motion - including possible Alfvén waves and nanojets - in the lower and middle corona that could shed light on coronal heating processes and the formation and stability of coronal structures. Our MWIR observations of a cool prominence and hot coronal active region plasma will be combined with spectra from the AIR-Spec instrument, flown concurrently on NCAR's HIAPER GV. We review the WB-57 eclipse mission and the current results of analysis on the visible and IR coronal measurements, along with an outlook for future analysis and missions.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E.526C