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Sweet Solar SAP: Boiling Down the Thermal Energy Content of Supra-Arcade Plasma Ashley Armstrong Advisor: Dr. Kathy Reeves Solar REU Summer 2012
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Overview What are solar flares and how are they classified? Where and what is supra-arcade plasma? My work estimating the thermal energy of the supra-arcade plasma
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What is a solar flare? Magnetic reconnection is assumed to drive flare events General brightening of electromagnetic spectrum Material in the flare reaches T≥10 7 K Often detected and classified by GOES
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Solar Flare Model Reeves, ApJ, 2006 X Where’s the SAP?
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X1.5 Flare in AR9906 21 April 2002 TRACE 195Å
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Prior Observations McKenzie & Hudson, ApJ, 1999 M5.2 20 January 1999 Yohkoh: SXT Gallagher, et al., Solar Physics, 2002 X1.5 21 April 2002 TRACE C4.9 5 November 2010 SDO: AIA AIA 131 2010-11-05 13:47:57.620 Reeves & Golub, ApJ, 2011
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Project Motivation Neupert Effect Implies peak X-ray flux will be directly proportional to total thermal energy released Reeves & Moats, ApJ, 2010 Found power law relation instead F peak ∼ E α (1.54 ≤ α ≤ 2.54) Hudson, Space Sci Review, 2011 + HXT * GOES Derivative
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Reeves & Moats, 2010 α = 2.54α = 2.16 α = 1.81α = 1.54 Reeves & Moats, ApJ, 2010
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Project Goal Estimate the thermal energy content of supra- arcade plasma. Serves as approximation for the total thermal energy input into the flare Use observations to test modeling results E th = 3Nk b T
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Location Near limb Not rotated behind disk GOES Class C, M, X Hottest Plasma Temperatures Present in 131 Å Absent from 171 Å Step 1: Event Selection
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AIA Response Functions 131 Å 171 Å 131 Å Response Function171 Å Response Function Overlap Intensity (dn cm 5 / sec) Log Temperature (K)
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Contrasting AIA Data AIA 131ÅAIA 171Å 8 March 2011
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Date & TimeGOES Class 8 March 2011 Peak Time: 18:28 UT M4.4 8 March 2011 Peak Time: 20:16 UT M1.4 4 November 2011 Peak Time: 01:01 UT C5.4 Selected Events AIA 131 Å
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Step 2: Capturing the SAP! AIA 131 Å 131 Å Contour335 Å ContourSAP Pixels 4 November 2011 20:11:04UT
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Step 2: Capturing the SAP! 18:56:21 2011 November 3 X
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Step 3: Estimate Line-of- Sight Utilizing STEREO A & B in 195 Å STEREO A 195 Å
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Step 4: Finding Thermal Energy Content Assumptions Constant line-of-sight depth All plasma at T = 11 MK Data from SAP pixels Use emission measure of each pixel to obtain particle density (n) The number of pixels in SAP region and line-of-sight give an estimate of the volume (V) Total number of particles: N = nV E th = 3Nk b T EM ~ ∫n 2 dl
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Results & Discussion
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Model lines from Reeves & Moats, 2010
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Conclusions Initial observations roughly support the power law relation between flux and thermal energy, as proposed by Reeves & Moats, 2010 Discrepancies exist between the thermal energy in the observations and modeling Future analysis of many more flares is needed before the power law relation can be conclusively supported
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Acknowledgments Dr. Kathy Reeves NSF (grant number ATM-0851866) NSF (grant number AGS-1156076) (Plasma Heating During Coronal Mass Ejections, Nick Murphy PI). CFA Astronomy REU Coordinators and Dr. Ed Deluca SSXG & Admins Fellow astronomy and solar interns THANK YOU!
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