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
Loops-6, Belgium, June 2013
Photo: Giulio Del Zanna
Characteristic loop structures for solar active regions
• 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?
• Very large ‘Fan’ loops reach far out into the corona, possibly joining remote active regions.
SDO/AIA Observations
ARE ALL THESE LOOPS HEATED IN THE SAME WAY???
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
• 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 chromospheric lines
• Very good diagnostics: EM, Ne, flows, abundances
Spectroscopic Instruments
: :
TRACE image – 1” res
SOHO/CDS – Mg IX - 6” res
CDS and TRACE: off limb AR quiescent loops (1MK)
• 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
Del Zanna and Mason (2003), Del Zanna (2003)
Emission measure loci plot using CDS data, showing near isothermal temperature (Del Zanna & Mason, 2003)
CDS: ‘warm’ 1MK Quiescent AR Loop
Hinode/EIS spectrum • Hinode/EIS
spectra are dominated by coronal ions (iron, particularly)
Young, Mason et al. (2007, PASJ)
Active region density mapPeter Young, 2007
The high quality of the
EIS data makes density maps
relatively easy to generate
Hinode EIS - temperature and density map for a limb AR
Average electron density map from FeXIII lines
Temperature map from FeXVI/FeXVRed is Log T = 6.7, yellow is Log T= 6.5
Hot, dense AR cores are clearly seen with EIS. XRT shows ‘dynamic’ activity.
O’Dwyer et al, 2011
Impulsive heating, nanoflare trains Klimchuk, Bradshaw, Cargill, Reep
Fix: • Loop length: 2L = 80 Mm• Power: 4 10-3 ergs cm-3 s-1
• Triangular pulse: width 100 sec.
Vary:• Delay between nanoflares
Diagnostics• Tmax, EM(Tmax)• EM ~ Ta, T < Tmax
• EM ~ Tb, T > Tmax
log E
M (
cm-5)
log T
log T
EM(T) of Inter-moss: Tripathi, Mason and Klimchuk, 2011
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).
Theory versus observations: hot core loopsTripathi, Klimchuk & Mason, 2011
EBTEL SIMULATIONS
Loop half length = 2.4x109 cmDuration of nanoflare = 500s Amplitude = 0.04 erg cm-3 s-1 Repetition time = every 8000sConstant low level heating = 10-6 erg cm-3 s-1
slope
• 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.
Age dependence of EM distribution in AR coresTripathi, D., O’Dwyer, B. and Mason, H.E., 2013
NOAA 11193: AIARotation 1 19-Apr-2011 Rotation 2 16-May-2011
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 ± 0.32Ratio = 22 ± 12
From log T = 6.0 to log T = 6.5
Slope = 2.14 ± 0.53Ratio = 9 ± 4
Log Ne = 9.7 Log Ne = 9.0
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 ± 0.12Ratio = 50 ± 11
From log T = 6.0 to log T = 6.5
Slope = 2.81 ± 0.17Ratio = 49 ± 14
Errors in the EM analyses.
Observational errors - EIS (or SDO) calibration- Blends
Errors in the EM/DEM methods-MCMC-Giulio’s method-EM Loci-EM Pottasch-Other methods
Errors in the atomic data-Ionisation balance-Radiative data-electron collision data
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
Comparison between MCMC and Pottasch EM Methods
Tripathi, D. and Ali, S.M., 2013
Comparison between MCMC and Pottasch EM Methods
Tripathi, D. and Ali, S.M., 2013
WARNING: Pottasch EM is only valid if the plasma is multi-thermalMCMC not reliable at low temperatures
Multi-thermal Emission in ARsDel Zanna, 2013
2010 Oct 26 SDO/AIA
171A 193A 335A
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
Errors? Gennou et al, 2013: Emission Measure Slope
Probability of the true slope given an observed slope =
3
Uncertainty: ~ 1.1
Guennou et al. (2013)
slope
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?
New Ionisation Balance (Ni ions)
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.
CHIANTI V7.1 and CHIANTI V8
G. Del Zanna
Scattering calculation for Fe XII calculations: Fe XII
Serious problems with the Fe XII spectrum.
Many calculations:Flower (1977)
Binello et al (several papers) Storey, Del Zanna, Mason (2005)
Del Zanna (2012)
EUV
4S3/2, 2D3/2, 2D5/2, 2P1/2, 2P3/2
2D3/2
4P1/2
4P3/2
2P1/2
SO
FeXII – Atomic Data re-visited (yet again!!)
Mason & Del Zanna - IRIS meeting 2012
New CC
Old CC
UK APAP Team O’Dwyer, Del Zanna, Badnell, Mason and Storey, 2012, A&A, 537, 22Atomic 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 dataThe previous R-matrix calculation (Storey et al. 2004) has been extended to include all main n=4 levels (for the soft X-rays)
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.
CHIANTI - Fe XII density diagnostics
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