Solar flares occur when a large amount of energy is converted into X-rays, heat, and supersonic fluid motion. Prior to the flare this energy is stored as magnetic field filling the atmosphere above sunspots and related features called active regions. The energy is released suddenly when an electric field changes the connectivity of several coronal magnetic field lines, which then retract rapidly. The fluid in these field line moves faster than the speed of sound and therefore creates shocks, which are believed to heat the plasma to tens of millions of Kelvins. In this project we will run numerical simulations to model this process.
PREFT, Post-Reconnection Evolution of a Flux Tube, is a simulation written by Professor Longcope that simulates the properties (temperature, density, pressure, etc.) of a flux tube post reconnection and during the retraction of the flux tube. One distinguishing feature of PREFT is that it includes a crude chromosphere that acts as a pool of material that is able to evaporate. Chromospheric evaporation ensues as the feet of the flux tube are heated by compresive shocks, and thus, post-retraction, PREFT is still able to simulate changes in flux tube properties as the evaporated material makes its way to the top of the loop. In the references is a paper from Professor Longcope that outlines PREFT and compares it to other ways to simulate solar flares, such as ad-hoc loop top heating mechanisms.
This summer, I have been working to both simulate an observed flare of interest while also trying to run a version of PREFT that has been modified to include drag on the flux tube. Drag has a drastic influence on the flux tube's properties in the simulations, so it's been valuable to compare the results of simulations depending on the amount of drag the simulation can introduce (a free parameter we can change).
Here you can find the presentations that I have made throughout the summer as progress reports or formal presentations presented to the whole REU group. These include crude information about my project and quick information about some of the work I have been doing.
| Week 4 Progress Presentation | Midterm Presentation | Final Presentation |
Affiliation: Department of Astrophysical and Planetary Sciences -- University of Colorado at Boulder
Email: patrick.mccreery@colorado.edu
Office: Barnard 252
How gas-dynamic flare models powered by Petschek reconnection differ from those with ad hoc energy sources -- Dana Longcope, Jim Klimchuk