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Published byAmaya Orsborn Modified about 1 year ago

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Evaporation driven by thermal conduction Heidi Dritschel REU student working in collaboration with Sean Brannon and Professor Longcope at MSU.

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Background Magnetic reconnection triggers solar flares Magnetic tension flattens out reconnected field lines Kinetic energy produced generates hydrodynamic shock Post shock hot loop top forms large temperature gradient Thermal conduction front formed to smooth out large temperature gradient

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why shocks? Loop contraction releases magnetic free energy 90% of energy goes to bulk fluid motion (kinetic energy) 10% of energy is thermal (heat)

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Background Thermal conduction front moves ahead of propagating shock Increase in pressure and temperature of chromospheric material (solar flare and coronal temperatures) Pressure gradient drives heated chromospheric plasma to expand up into coronal loops Coronal loops filled with dense plasma brightening seen in 1600 Angstroms Pressure peak formed also drives down-flowing material: condensation front

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model 1D hydrodynamic model Tube divided in three: chromosphere, transition region and corona Loop symmetry assumed: model half loop structure Piston shock sent through tube modeling rapid (supersonic) plasma compression that would generate a shock

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MODEL Modeling conduction driven chromospheric evaporation : C-class flares (small) Semi-implicit code Radiative effects ignored Non-uniform static grid Heat source and sink added to tube generating artificial chromosphere Prior model assumed uniform cross-section

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Modified model Sun surface, in theory, thought of as covered in magnetic point sources Represent these positive point sources scattered in hexagonal fashion Controlled by geometry of magnetic field

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Modified model Cross-section taken of a point source Different curvature RHS: separatrix surface LHS: separator Modified our uniform model to have varying cross-sectional areas A and C

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area a profile Altered position of expanded region of nozzle relative to the transition region by 0.1 to the RHS and LHS

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Area c profile Altered position of expanded region of nozzle relative to the transition region shifting it to the LHS by 0.1 and 0.2 and the RHS by 0.1

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movie of a run of modified model Loop A as originally positioned

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results DEM Loop C shifted to the left by 0.2

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results Velocity vs Temp: Loop C shifted to the left by 0.2

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results down-flowing material Up-flow material Post-Shock Chromospheric Shock

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results Loop A EM (evap) [cm -5 ] EM (total) [cm -5 ] x x x x x x x x Loop C EM(evap) [cm -5 ] EM (total) [cm -5 ] x x x x x x x x x x10 36

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results

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RESULTS

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results

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Results

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