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Sweet Solar SAP: Boiling Down the Thermal Energy Content of Supra-Arcade Plasma

Sweet Solar SAP: Boiling Down the Thermal Energy Content of Supra-Arcade Plasma. Ashley Armstrong Advisor: Dr. Kathy Reeves Solar REU Summer 2012. Overview. What are solar flares and how are they classified? Where and what is supra-arcade plasma?

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Sweet Solar SAP: Boiling Down the Thermal Energy Content of Supra-Arcade Plasma

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  1. Sweet Solar SAP:Boiling Down the Thermal Energy Content of Supra-Arcade Plasma • Ashley Armstrong • Advisor: Dr. Kathy Reeves • Solar REU Summer 2012

  2. 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

  3. What is a solar flare? • Magnetic reconnection is assumed to drive flare events • General brightening of electromagnetic spectrum • Material in the flare reaches T≥107 K • Often detected and classified by GOES

  4. Solar Flare Model Where’s the SAP? X Reeves, ApJ, 2006

  5. X1.5 Flare in AR990621 April 2002 TRACE 195Å

  6. Prior Observations M5.2 20 January 1999 Yohkoh: SXT 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 McKenzie & Hudson, ApJ, 1999 Gallagher, et al., Solar Physics, 2002

  7. 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 • Fpeak ∼ Eα (1.54 ≤ α ≤ 2.54) + HXT * GOES Derivative Hudson, Space Sci Review, 2011

  8. 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 Eth = 3NkbT

  9. Step 1: Event Selection • Location • Near limb • Not rotated behind disk • GOES Class • C, M, X • Hottest Plasma Temperatures • Present in 131 Å • Absent from 171 Å

  10. Overlap 131 Å 171 Å AIA Response Functions Intensity (dn cm5 / sec) Log Temperature (K) 131 Å Response Function 171 Å Response Function Intensity (dn cm5 / sec) Intensity (dn cm5 / sec) Log Temperature (K) Log Temperature (K)

  11. Contrasting AIA Data AIA 131Å AIA 171Å 8 March 2011

  12. Selected Events AIA 131 Å AIA 131 Å

  13. Step 2: Capturing the SAP! AIA 131 Å AIA 131 Å AIA 131 Å 131 Å Contour 335 Å Contour SAP Pixels 4 November 2011 20:11:04UT

  14. Step 3: Estimate Line-of-Sight STEREO A 195 Å Utilizing STEREO A & B in 195 Å

  15. 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 Eth = 3NkbT EM ~ ∫n2dl

  16. Results & Discussion

  17. Model lines from Reeves & Moats, 2010

  18. 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

  19. 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!

  20. Questions ?

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