Probing Energy Release of Solar Flares M. Prijatelj Carnegie Mellon University Advisors: B. Chen, P. Jibben (SAO) Overview •  MoEvaEons •  Standard Flare Model –  Flux rope erupEon –  MagneEc reconnecEon –  Flare emissions •  Type III Radio Bursts •  Instruments –  VLA, AIA, HMI, & RHESSI •  Observed Flare •  Dynamic Imaging Spectroscopy •  Results & Conclusions 2 MoEvaEons •  InvesEgate basic solar flare physics –  Energy release, parEcle acceleraEon & transportaEon •  Understand flares’ cause and impact –  Analyzing flare parEcles •  Map reconnected coronal magneEc field lines –  Dynamic Imaging Spectroscopy Figure 1: AIA image of the sun, wavelength 171Å 3 Standard Flare Model •  Flux rope erupEon •  MagneEc reconnecEon •  Flare emissions Figure 2: Large solar filament erupEon h\p://www.nasa.gov/images/content/683943main_erupEon-­‐zoom.jpg 4 Flux Rope ErupEon •  Flux ropes form within solar atmosphere •  Flux rope loses equilibrium & erupts –  Magnetohydrodynamic (MHD) instabiliEes –  MagneEc reconnecEons •  Field lines reconnect following erupEon Figure 3: Diagram of erupEon & magneEc reconnecEon h\p://solarmuri.ssl.berkeley.edu/~hhudson/cartoons/thepages/Shibata.html 5 MagneEc ReconnecEon •  Inwardly moving anEparallel field lines connect •  Reconnected lines flow outward •  MagneEc energy release –  Thermal energy –  KineEc energy •  ParEcle acceleraEon •  Bulk moEon Figure 4: AnimaEon of anEparallel magneEc field lines undergoing magneEc reconnecEon h\ps://upload.wikimedia.org/wikipedia/commons/2/24/ReconnecEon.gif 6 Flare Emissions RADIO BURSTS Figure 5: RadiaEon emissions generated by magneEc reconnecEon h\p://solarmuri.ssl.berkeley.edu/~hhudson/cartoons/thepages/Svestka.html 7 –  Generate Langmuir waves near plasma frequency fp –  Emit radio bursts near fp or 2fp •  Electron beam direcEon affects burst drij direcEon –  Upward ! NegaEve –  Downward ! PosiEve Frequency •  Created by flare-­‐
accelerated electrons Downward Upward Type III Radio Bursts Chromosphere Time Figure 6: Trajectories of electron beams (green) from reconnecEon site (red X) along magneEc field lines (blue) with respect to frequency drijs. 8 Imaging Instruments •  Karl G. Jansky Very Large Array (VLA): Radio wavelengths •  Atmospheric Imaging Assembly (AIA): Extreme ultraviolet •  Helioseismic & MagneEc Imager (HMI): MagneEc field •  Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI): Soj & hard X-­‐ray, gamma rays 9 VLA Data •  Broadband dynamic imaging spectroscopy –  Large instantaneous bandwidth –  High temporal resoluEon –  High spectral resoluEon –  Full Fourier synthesis imaging •  Dynamic Spectrum & Imaging Figure 7: SpaEal imaging of a type III radio burst. 10 AIA, HMI, & RHESSI •  AIA images solar chromosphere & corona –  Seven extreme ultraviolet (EUV) channels •  HMI photospheric magneEc field measurements –  White posiEve (outward) polarity –  Black negaEve (inward) polarity •  RHESSI images soj X-­‐rays to gamma rays –  X-­‐rays primarily emi\ed by accelerated electrons Figure 8: Data of C7.2 flare in various wavelengths (clockwise from top lej): AIA 171 Å, HMI line-­‐of-­‐sight magnetogram, RHESSI HXR data 11 Observed Solar Flare •  C7.2 solar flare •  Observed Nov. 1, 2014 •  Impulsive phase of the flare –  Interested in type III radio bursts Figure 9: GOES X-­‐ray flux data at Eme of C7.2 flare, 2014-­‐11-­‐01, impulsive phase highlighted h\p://www.polarlicht-­‐vorhersage.de/goes/2014-­‐11-­‐01_163500_2014-­‐11-­‐01_172600.png 12 Dynamic Imaging Spectroscopy Leading Edge Figure 10: Dynamic spectrum during C7.2 flare, with closer inspecEon of a negaEvely-­‐drijing type III burst, indicaEng an upward-­‐moving electron beam, and a spaEal image of the radio burst. 13 AIA Movie of C7.2 Flare Figure 11: AIA 171 Å movie of C7.2 solar flare at 16:37:04 on 2014-­‐11-­‐01 14 AIA & HMI Comparison 16:35:00.340 16:42:48.340 Flare Ribbons 17:10:00.340 Post-­‐Flare Loops Flux Rope Flux Rope Sigmoid Figure 12: AIA 171 Å images before, during, and ajer the solar flare. HMI posiEve (white) & negaEve (black) polar regions are contoured. 15 Results & Conclusions •  Findings correspond with standard flare model Flare Ribbons –  ReconnecEon region trails erupEng flux rope (AIA) –  Electron beams follow reconnected field lines •  Downward beams create HXR footpoints •  Type III bursts from upward & downward beams Flux Rope HXR Emissions Radio Frequency Maxima Figure 13: AIA 171 Å flare image with overlaid VLA radio emission maxima & single flux contour (colored dots & blue contour, respecEvely), HMI contours (posiEve regions white, negaEve regions black), and RHESSI contours (red contours). The magneEc field lines are purple lines, the “X-­‐point” is at the yellow explosion, & the electron beam trajectories are blue arrows. 16 Summary •  VLA indirectly maps reconnected magneEc fields –  Radio emissions determine electron beam trajectories –  Trajectories follow reconnected field lines •  AIA, HMI, & RHESSI provide addiEonal context •  Data juxtaposiEon demonstrates standard flare model 17 Acknowledgements •  NSF-­‐REU solar physics program at SAO, grant number AGS-­‐1263241 •  NASA contract SP02H1701R from Lockheed-­‐MarEn to SAO 18 Special Thanks To •  Henry “ Trae” Winter & Kathy Reeves •  Bin Chen & Patricia Jibben •  Everyone else at Harvard CfA & SAO 19 AddiEonal InformaEon •  AIA images solar chromosphere & corona –
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EnEre solar disk Seven extreme ultraviolet (EUV) channels Temperature range from 20 000K to 20 000 000 K 12 second cadence 1.5 arcsec resoluEon •  Field lines flow posiEve to negaEve –  “Footpoints” –  Plasma flow along field lines •  RHESSI: –  X-­‐rays typically emi\ed at footpoint •  Accelerated electrons collide with chromosphere 20