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Investigating the Momentum Processes of Solar Eruptions Using Photospheric Magnetic Field Observations

Event Details

Event Dates: 

Thursday, March 16, 2017 - 4:00pm

Seminar Location: 

  • JILA Auditorium

Speaker Name(s): 

Xudong Sun

Speaker Affiliation(s): 

Stanford University
Seminar Type/Subject

Scientific Seminar Type: 

  • Astrophysical & Planetary Sciences Seminar

Event Details & Abstract: 

The solar active region photospheric magnetic field evolves rapidly during major eruptive events, suggesting appreciable feedback from the corona. Using high-cadence vector magnetogram sequence, multi-wavelength coronal imaging, and numerical simulation, I will show how the observed photospheric "magnetic imprints" can be used to estimate the impulse of the Lorentz force that accelerates the coronal mass ejection (CME) plasma. In an archetypical event, the Lorentz force correlates well with the CME acceleration, but the total force impulse surprisingly exceeds the CME momentum by almost two orders of magnitude. I propose a "gentle photospheric upwelling" scenario, where most of the Lorentz force is trapped in the lower atmosphere layer, counter-balanced by gravity of the upwelled mass. This unexpected effect dominates the momentum processes, but is negligible for the energy budget. I will discuss our follow-up project, how the upcoming high-sensitivity observations and new- generation numerical models may help elucidate the problem.