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Loops-6, Belgium, June 2013

Age dependence of EM in AR Cores... and... Some thoughts on the Accuracy of Atomic Data Helen Mason, Durgesh Tripathi, Brendan O’Dwyer and Giulio Del Zanna. Photo: Giulio Del Zanna. Loops-6, Belgium, June 2013.

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Loops-6, Belgium, June 2013

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  1. Age dependence of EM in AR Cores... and...Some thoughts on the Accuracy of Atomic Data Helen Mason, Durgesh Tripathi, Brendan O’Dwyer and Giulio Del Zanna Photo: Giulio Del Zanna Loops-6, Belgium, June 2013

  2. Large 1MK loops (171A) seem to be ‘almost isothermal’ and ‘spatially resolved’ by present day instruments such as TRACE, EIS, SDO/AIA. • Are they? • Check with HiC at 171A • The hot core loops (3MK?) do not seem to be so well resolved. • Look same in SDO/AIA and HiC. • We can study their footpoints regions (moss regions). • Micro-flare activity and Dynamic core loops – mini-post-flare? • Verylarge ‘Fan’ loops reach far out into the corona, possibly joining remote active regions. Characteristic loop structures for solar active regions SDO/AIA Observations ARE ALL THESE LOOPS HEATED IN THE SAME WAY???

  3. Imaging versus spectroscopic observationsImaging instruments • TRACE, EIT, Stereo/EUVI, SDO/AIA, HiC • Intensity variations...flows, waves or pulses? • Intensity changes – Ne or Te? • Several spectral lines contributing to some wavelength bands? • High cadence and good spatial coverage • Relatively straightforward to analyse Spectroscopic Instruments • SoHO/CDS and SUMER, Hinode/EIS, Coronal visible lines • High cadence at expense of spatial coverage...one slit position • Uncertainties – jitter, line blending, absolute wavelengths, other instrumental effects – point spread function? • A nightmare to analyse, very labour intensive... • SUMER – absolute wavelengths relative to chromosphericlines • Very good diagnostics: EM, Ne, flows, abundances

  4. CDS and TRACE: off limb AR quiescent loops (1MK) : : Del Zanna and Mason (2003), Del Zanna (2003) TRACE image – 1” res SOHO/CDS – Mg IX - 6” res • Background subtraction is crucial • 1 MK TRACE loops, are isothermal across the loop, but have 0.7 MK footpoints with Ne of around 2 x 109 cm-3. • Imaging at 1” seems to resolve single flux tubes

  5. CDS: ‘warm’ 1MK Quiescent AR Loop Emission measure loci plot using CDS data, showing near isothermal temperature (Del Zanna & Mason, 2003)

  6. Hinode/EIS spectrum • Hinode/EIS spectra are dominated by coronal ions (iron, particularly) Young, Mason et al. (2007, PASJ)

  7. Active region density mapPeter Young, 2007 The high quality of the EIS data makes density maps relatively easy to generate

  8. O’Dwyer et al, 2011 Average electron density map from FeXIII lines Hinode EIS - temperature and density map for a limb AR Temperature map from FeXVI/FeXV Red is Log T = 6.7, yellow is Log T= 6.5 Hot, dense AR cores are clearly seen with EIS. XRT shows ‘dynamic’ activity.

  9. Impulsive heating, nanoflare trains Klimchuk, Bradshaw, Cargill, Reep • Diagnostics • Tmax, EM(Tmax) • EM ~ Ta, T < Tmax • EM ~ Tb, T > Tmax Fix: • Loop length: 2L = 80 Mm • Power: 4 10-3 ergs cm-3 s-1 • Triangular pulse: width 100 sec. Vary: • Delay between nanoflares

  10. EM(T) of Inter-moss: Tripathi, Mason and Klimchuk, 2011 log T log EM (cm-5) log T

  11. Theory versus observations: hot core loopsTripathi, Klimchuk & Mason, 2011 slope a HINODE/EIS EM Data points are the average of the EM of regions A, B, C subtracted by the average of EM for Bkg1 and Bkg2 reduced by a factor 4 (see next slide). EBTEL SIMULATIONS Loop half length = 2.4x109 cm Duration of nanoflare = 500s Amplitude = 0.04 erg cm-3 s-1 Repetition time = every 8000s Constant low level heating = 10-6 erg cm-3 s-1

  12. Age dependence of EM distribution in AR cores Tripathi, D., O’Dwyer, B. and Mason, H.E., 2013 • Active region 11193 • First rotation – April 19th, 2011 • Second rotation – May 16th, 2011 • SDO available • Active Region 11057 • First rotation – March 28th, 2010 • Second rotation – April 27th, 2010 • NO SDO available Very carefully selected Inter-moss MCMC method was used to derive the slope and Ratio.

  13. Rotation 1 19-Apr-2011 Rotation 2 16-May-2011 NOAA 11193: AIA

  14. AR 11193high temperature emission and slope decreases with age:high to low frequency nanoflares? From log T = 6.0 to log T = 6.5 Slope = 2.61 ± 0.32 Ratio = 22 ± 12 From log T = 6.0 to log T = 6.5 Slope = 2.14 ± 0.53 Ratio = 9 ± 4 Log Ne = 9.0 Log Ne = 9.7

  15. AR 11057high temperature emission and slope decreases with age:high to low frequency nanoflares? From log T = 6.0 to log T = 6.5 Slope = 3.01 ± 0.12 Ratio = 50 ± 11 From log T = 6.0 to log T = 6.5 Slope = 2.81 ± 0.17 Ratio = 49 ± 14

  16. Errors in the EM analyses. Observational errors - EIS (or SDO) calibration - Blends • Errors in the atomic data • Ionisation balance • Radiative data • electron collision data Errors in the EM/DEM methods -MCMC -Giulio’s method -EM Loci -EM Pottasch -Other methods Other Uncertainties -elemental abundances -equilibrium? • How to deal with all of these issues? • CHIANTI – v7.1 (soon V8) • Assess errors on individual lines • Look for consistency in results

  17. Comparison between MCMC and Pottasch EM MethodsTripathi, D. and Ali, S.M., 2013

  18. Comparison between MCMC and Pottasch EM MethodsTripathi, D. and Ali, S.M., 2013 WARNING: Pottasch EM is only valid if the plasma is multi-thermal MCMC not reliable at low temperatures

  19. Multi-thermal Emission in ARsDel Zanna, 2013 2010 Oct 26 SDO/AIA 171A 193A 335A

  20. Multi-thermal Emission in ARsDel Zanna, 2013 EM for 3MK AR Core loops: Lhs: T_max; rhs: T_eff ----- slope of 3.4 Note consistency of EM for different ion stages of iron

  21. Errors? Gennou et al, 2013: Emission Measure Slope slope a Probability of the true slope given an observed slope a = 3 Uncertainty: Da ~ 1.1 Guennou et al. (2013)

  22. CHIANTI An atomic database for astrophysics • UK, USA, Italy • First database to make atomic data freely available for astrophysics • First released in 1996 • Just released v7.1 Landi et al, 2013, ApJ, 763 • Improved coverage in X-ray range (addressing 94A) • Over 1,000 citation • CHIANTI V8 – 2013?

  23. New Ionisation Balance (Ni ions)

  24. CHIANTI V7.1 and CHIANTI V8 CHIANTI v.7.1: DW data (Landi & Dere 2013) + identifications of Del Zanna (2012). R-matrix data (Del Zanna+2012) provide increased intensities. They will be available in v.8.

  25. G. Del Zanna • Serious problems with the • Fe XII spectrum. • Many calculations: • Flower (1977) • Binello et al (several papers) • Storey, Del Zanna, Mason (2005) • Del Zanna (2012) Scattering calculation for Fe XII calculations: Fe XII 2D3/2 4P1/2 4P3/2 2P1/2 SO EUV 4S3/2, 2D3/2, 2D5/2, 2P1/2, 2P3/2

  26. Mason & Del Zanna - IRIS meeting 2012 UK APAP Team O’Dwyer, Del Zanna, Badnell, Mason and Storey, 2012, A&A, 537, 22 Atomic data for the X-ray lines of Fe VIII and Fe IX (for SDO/AIA, 94A) Del Zanna, Storey, Badnell and Mason (2012, in press) - new Fe XII atomic data The previous R-matrix calculation (Storey et al. 2004) has been extended to include all main n=4 levels (for the soft X-rays) FeXII – Atomic Data re-visited (yet again!!) New CC Old CC

  27. CHIANTI- Fe XII density diagnostics This plot shows how the density derived from a single, quiet Sun off-limb data-set has changed with time using the Fe XII λ186.88/λ195.12 and Fe XIII λ203.82/λ202.04 density diagnostics. The changes are due to improvements in the atomic data models in CHIANTI.

  28. Summary • More work needs to be done on EM tracking AR evolution • Errors in the various DEM methods need checking carefully • New EIS calibration is very important • SDO/AIA responses now much better understood • Abundances can give problems • Atomic data are much better that they were! • Benchmarking CHIANTI v7.1+ gives good results • Errors need to be judged for each spectral line/transition WE NEED HIGHER SPATIAL RESOLUTION AND HIGHER CADENCE SPECTRAL OBSERVATIONS IRIS, SOLAR-C and Solar Orbiter

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