2011 Solar Physics REU Final Research Report

X-Ray Observation and Analysis of a M1.7 Class FlareCourtney PeckAdvisors: Jiong Qiu and Wenjuan Liu

Project OutlineOverview of Solar FlaresSolar Flare ModelObserving Solar FlaresRHESSI ObservationAnalyzing Lightcurve DataMonitoring Footpoints and Loop-topCalculating SpectraEBTEL/CHIANTI PredictionsComparing Theory and Observations

Solar Flare BasicsLarge release of magnetic energy at an active region causing radiationEmission ranges from radio to gamma raysClassified by soft x-ray flux: B, C, M, XTwo groups: small, compact large, two ribbon

Solar Flare ModelMagnetic field emerges from solar surface and forms active regionAs field emerges, reconnection occurs and releases energyLoop heating -> Thermal radiationParticle acceleration -> Bremsstrahlung radiationSubsequent field lines go through reconnection giving illusion of moving footpoints and growing loops

(Forbes)Viewing Solar FlaresMonitoring Loops and FootpointsUV and EUVThermal radiation -> loop and footpoint heatingX-Ray: Soft and HardSoft X-ray: 3-20keVThermal radiation -> loop-top heatingHard X-ray: >10keVNon-thermal radiation-> Bremsstrahlung radiation at footpoints

RHESSI X-Ray ObservationsBridges footpoint and loop-top observations using HXR and SXRShows evolution of top and bottom of flareHXRHighest energy band commonly observed in flareObserves footpointsFirst peak in lightcurve of flare eventSXRLower energy than HXRObserves loop-top radiationGradual rise of lightcurve to flare maximumFlare to be StudiedMarch 7th, 2011M1.7 flare in active region 11166Use RHESSI Software to construct an understanding of flareLightcurveImageFootpoint movementLoop-top evolutionSpectra

Using RHESSI LightcurveLightcurveTime history of SXR and HXRDecide how to make imagesPeaksAttenuatorsFootpointsFirst high-energy peakLoop-topsSlowly rising lower energy peaks

Where are the footpoints?

Apparently Not Here

All high energy HXR (>25keV) particles indicated in lightcurve were a result of different flareOther flare region not recognized by other flare catalogsComplicates analysis a bitNothing HereSolutionCorrecting the LightcurvesMake images from both flaring regionsUse RHESSI to compute flux in each regionMake computer program to determine ratio of the flux in each region to total fluxMultiply original lightcurve by ratio to get lightcurve for our regionImage Loop-top EvolutionFootpoints not seen in this flareCalculate Theoretical SpectraCan no longer use RHESSI software to calculate spectraUse EBTEL/CHIANTI to calculate theoretical spectra and lightcurve Compare theoretical lightcurve to actual lightcurves to confirm spectra

Correcting Lightcurve for Extra Flare

Correcting Lightcurve for Extra Flare

Correcting Lightcurve for Extra Flare

All non-thermal radiation not in our flare!

Monitoring loop-top Evolution

All energy associated with loop-tops not footpoints as shown by lightcurve correction. Flare is therefore a thermal flare.Comparing New Lightcurve with TheoryEBTELUse actual UV data to best fit to EBTEL model Find best-fit parameters for EBTELConsidered thermal flare -> FortunatelyFind density and temperate parameters for loopsCHIANTIAtomic databaseUses EBTEL parameters to calculate differential emission measure (DEM)Amount of plasma emitting radiation at a given temperature rangePlot predicted lightcurve and spectra for RHESSI energy rangesActual vs. Theoretical

Actual vs. Theoretical

Actual vs. Theoretical

Actual vs. Theoretical

Actual vs. Theoretical

Actual vs. Theoretical

ConclusionsPredicted lightcurves for RHESSI closely correlated to actual lightcurves after correcting for extra flareFirst time RHESSI lightcurves predicted with EBTEL DEM and CHIANTIEBTEL/CHIANTI used DEM which better predicted the changing temperature across loops than isothermal models used by RHESSIIsothermal model assumes constant temperature and density across all loops -> not often trueBetter model for spectra than RHESSI spectra due to extra flare and strong correlation of lightcurves