[IGPP Everyone] Reminder - Today - SPACE SCIENCE SEMINAR - Spring Quarter - 3:30pm -Friday May 1, 2020

[Marjorie Sowmendran]

Today ! 




SPACE PHYSICS SEMINAR 




USE THE CCLE ZOOM LINK PROVIDED BELOW 








https://ccle.ucla.edu/mod/zoom/view.php?id=2939559 





Date/Time: May 1, 2020/ 03:30 PM Pacific Time (US and Canada) 







SPACE PHYSICS SEMINAR 

DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES 

DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCES 

UNIVERSITY OF CALIFORNIA, LOS ANGELES 

(AOS M275B, EPSS M288B) 

Sun-grazing Comets as Solar Probes: Constraining the Magnetic Field and 
Plasma Conditions of the Solar Corona 





Yingdong Jia 




Department of Earth, Planetary, and Space Sciences, UCLA 







Abstract: Sun-grazing comets with perihelion distances of less than a few solar radii can serve as nature-made probes to the solar atmosphere. Recent examples included Comet C/2011 W3 (Lovejoy), which dived into the solar corona and survived its perihelion passage, exhibiting days of rich tail activity along its path. In general, the cometary material undergoes various stages of fierce thermal-chemical reactions on timescales of seconds to minutes. These reactions ionize cometary ions through successive charge states, as revealed by certain emission lines in extreme-ultraviolet images (e.g., from SDO/AIA and STEREO/EUVI). Such reaction processes are significantly affected by the ambient plasma and magnetic field conditions of the corona, which in turn can be constrained by modeling the structure of the comet tail, in comparison with observations. We combined three numerical models: a global corona model, a particle ablation model, and a cometary plasma interaction model into a unified framework to simulate the interaction of Sun-grazing comets in the low corona during several hours of the comet's perihelion trip. Constrained by imaging observations, we applied our framework to trace back the local condition of the ambient corona and its spatiotemporal variation. Our model shows the effect of the ambient magnetic field, velocity shear, and density in shaping the cometary tail. 




Friday May 1, 2020 




In-charge: C. T. Russell 






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