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Modeling Solar Flares Using Tapered Coronal Loops Natalie Larson Dr. Kathy Reeves, Dr. Trae Winter Harvard Smithsonian Center for Astrophysics Solar Physics REU 2010

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Modeling Solar Flares Using Tapered Coronal Loops

Natalie Larson Dr. Kathy Reeves, Dr. Trae Winter

Harvard Smithsonian Center for Astrophysics Solar Physics REU 2010

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What is a solar flare?Rapid, intense brightening in X-ray emissions

TRACE XRT

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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

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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

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Method•Generate flare using Kathy’s model

•Get Energy and Geometry•Put Energy and Geometry into Natalie’s Heating Function

•Trae’s model works with Natalie’s heating function to describe evolution of temperature and density in flare

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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

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Kathy’s Model

• Loss-of-equilibrium model

• Input: Original magnetic configuration, input energy

• Output: energy released and geometry of the loop

Reeves, Warren, and Forbes, 2007

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Kathy’s Model

• Output agrees well with observed flaresLin et. al., ApJ, 2005

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Trae’s Model: HyLoop

• HyLoop: The controller.

• SHReC: Solar Hydrodynamic Equation Codes (thermal particles)

• PATC: Particle Tracking Codes (non-thermal particles)

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My contribution

• Heating function

• Kathy’s code->Heating function<->Trae’s 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

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Results: GOES light curves

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Results: temperature and density

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Results: XRT light curves

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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 light curves and (simulated) input energy (need to model all loops with NT particles, and need to model more than one flare)

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Thank you!

• Kathy and Trae!

• CfA: Solar Group

• NSF

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References

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Evolution of Temperature and Pressure