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