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  • 1. Modeling Solar Flares Using Tapered Coronal Loops Natalie LarsonDr. Kathy Reeves, Dr. Trae Winter Harvard Smithsonian Center for AstrophysicsSolar Physics REU 2010

2. What is a solar flare?

  • Rapid, intense brightening in X-ray emissions

TRACEXRT 3. Closer view of solar flare

  • Magnetic field lines of two fields are joined, creating a new magnetic field configuration

http://cse.ssl.berkeley.edu/segwayed/lessons/exploring_magnetism/in_Solar_Flares/s4.html 4. The project: this summer

  • Modeling a flare with tapered loops causes:
    • More accurate representation of flare loop
    • Energy and density variations along the loop
    • Non-thermal particle mirroring

5. Method

  • Generate flare using Kathys model
  • Get Energy and Geometry
  • Put Energy and Geometry into Natalies Heating Function
  • Traes model works with Natalies heating function to describe evolution of temperature and density in flare

6. The project: long-term goals

    • Understand relationship between energy release and hard and soft X-rays
    • Amount of energy input that produces particular hard and soft X-ray light curves by varying energy input into model
    • Conditions under which Neupert Effect is seen
    • Relationship between peak soft X-ray flux and total energy input

7. Kathys Model

  • Loss-of-equilibrium model
  • Input: Original magnetic configuration, input energy
  • Output: energy released and geometry of the loop

Reeves, Warren, and Forbes, 2007 8. Kathys Model

  • Output agrees well with observed flares

Lin et. al., ApJ, 2005 9. Traes Model: HyLoop

  • HyLoop: The controller.
  • SHReC: Solar Hydrodynamic Equation Codes (thermal particles)
  • PATC: Particle Tracking Codes (non-thermal particles)

10. My contribution

  • Heating function
    • Kathys code->Heating functionTraes code
    • Uses Gaussian function to distribute energy over loop length
    • Uses triangle function for energy in the loop over time
  • GOES flux simulation:
    • Input: temperature and emission measure at each second
    • -> GOES module calculates flux (Watts/m^2)
    • Output: Sum of all flux in the flare at each second
  • Light curves, plots, analysis
  • Miscellaneous intermediate plots and validity-checking

11. Results: GOES light curves 12. Results: temperature and density 13. Results: XRT light curves 14. Future Work

  • Compare previous and new values for peak soft X-ray flux in flare to total energy input in flare (need to model more than one flare to do this)
  • Vary energy input in flare to find light curve that best fits observations to approximate real energy input in flare
  • Model entire flare in hard X-rays and compare light curve to derivative of the soft X-ray light curve (Neupert Effect)
    • Compare simulated and observed soft and hard X-ray lightcurves and (simulated) input energy (need to model all loops with NT particles, and need to model more than one flare)

15. Thank you!

  • Kathy and Trae!
  • CfA: Solar Group
  • NSF

16. References 17. Evolution of Temperature and Pressure