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Astronomy Colloquium - "Shedding light on planetary coronae using scattered UV emission"

Event Type
Astronomy Department
134 Astronomy
Mar 5, 2019   3:45 pm  
Dr. Lara Waldrop, UIUC
Rebecca Bare
Originating Calendar
Astronomy Colloquium Speaker Calendar

Knowledge of the spatial and kinetic distributions of atomic hydrogen (H) in terrestrial planetary coronae is required to assess the permanent loss of water reservoirs through gravitational H escape as well as to understand their role as a dynamic buffer against the solar-driven environment of interplanetary space.  Reliable specification of exospheric parameters at Earth and its closest neighbors Mars and Venus – whether analytically, numerically, or experimentally – is notoriously lacking, hindered mainly by the challenge of properly addressing the transition from efficient collisional thermalization of H atoms in the lower atmosphere to the nearly collisionless, non-Maxwellian exospheric regime that extends out to tens of planetary radii.  In this talk, I will describe recent advances in computational modeling of the radiative transport of scattered solar UV photons that better represent this transition.  Such tools enable more accurate interpretation of decades-worth of UV Lyman-alpha emission observations of the H coronae of the inner planets, and several examples of recent 2D and 3D data analyses will be used to demonstrate the current state-of-the-art, reveal surprising exospheric phenomenon, and motivate future work.

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