The effects of canopy expansion on chromospheric evaporation driven by thermal

conduction fronts

Authors: F. Rozpedek, S. R. Brannon, D. W. Longcope

Credit: M. Aschwanden et al. (LMSAL), TRACE, NASA

RD RDGDSGDS

RD accels plasma

GDS heats plasma to flare temp. @

loop top

Simulationregion

Chromosphere

Reconnection frees loop to

contract

~90% free mag. energy => bulk plasma motion(Longcope et al. 2009)

Flare loop dynamics

1-D “shocktube” model

•Model details:

•Static non-uniform grid:

• <1 km (chromosphere), ~10 km (corona), scales up in TR

•Include viscosity & Spitzer conductivity

•Neglect gravity & explicit radiative effects

•Simplified model atmosphere: temp. grad. @ const.

pressure

•Classical piston shock (tanh func. w/ Rankine-

Hugoniot)

Mp

Ms

ChromosphereT=0.01

CoronaT=1

Uniform pressure in TR

Trans. Reg.(TR)

GDS

Post-shockFluidinput

Model loop atmosphereChromosphere TR Corona

Time Evolution for the uniform tube

TCF

Time Evolution for the uniform tube

TCF

Time Evolution for the uniform tube

E

C

TCF

Time Evolution for the uniform tube

E

C

TCFC

E

Time Evolution for the uniform tubeE

C

TCF

CE

A

CB

TR ??

Question:Is there some observational quantity that would enable us to determine where the nozzle is located relative to the Transition Region?

The canopy expansion

Varying Area Profile

Nozzle below the TRNozzle at the centre

of the TR Nozzle above the TR

The area profile has a form of a piecewise linear function.

ThermalConduction

Front

ThermalConduction

Front

ThermalConduction

Front

Transsonic points(lower) (upper)

Transsonic points (lower) (upper)

Thank You