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35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Analysis of Potassium Abundance in
Selected Solar Flares
J. Sylwester, B. Sylwester (SRC, Poland)
K.J.H. Phillips (GSFC, USA)
J.L. Culhane (MSSL, UK) C. Brown (NRL, USA), J. Lang (RAL, UK)
A.I. Stepanov (IZMIRAN, Russia)
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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RESIK - instant collection of spectra
Bragg law: kλ =2d sinΘ
Рентгеновский Спектрометр с Изогнутыми Кристаллами
Measure spectra in range: 0.335 nm – 0.610 nm, instantly in all λ
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Well callibrated
RESIK, RHESSI, and GOES Spectra: 2003 April 26 flare
Brian Dennis & Ken Phillips
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Some example spectra from ~1000 reformatted
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Prompt analysis - isothermal approximation - T & EM
#1
#4 T from #1/#4 flux ratioEM from T and #4 flux(CHIANTI atomic data)
Dividing the photon flux by EM spectrum per unit EM (1044 cm-3)
Group spectra according to T and take averages
Continuum fromT and EM
Removing the continuum allows to study line fuxes
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Vicinity of K and Ar He-like tripletsLines + cont Lines Lines + cont Lines
K Ar
Gratio
Gratio
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Observed temperature dependence for K XVIII w
Polynomialfit
Excitation: MeweIon equil: Mazzotta
AK = 6.31 10-7
AK x 2
AK / 2
Line Flux above the continuum
(area)
divide by emission measure determined in the isothermal approximation
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Observed temperature dependence for Ar XVII w(S XV 1s2 – 1s6p contribution removed)
Polynomialfit
Excitation: MeweIon equil: Mazzotta
AAr = 5.62 10-6
AAr x 1.4
AAr x 2/3
Nearly perfect overlapping of the best fit with the theoretical dependence
Line Flux above the continuum
(area)
divide by emission measure determined in the isothermal approximation
1/5
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Differences „by eye”
AK < 1/3 average : 8 intense cases
AK > 1.8 x average : 8 intense cases
Similar T ~ 7 MK
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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relative line variability - T plots
4
K Ar
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Does K/Ar ratio correlate with…
NO ! NO !
C M
35th COSPAR Scientific Commission E1.9 Paris, 18-25 July 2004
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Conclusions
• Regular temperature behaviour of line emissivities experimental determination of emission functions (be aware of assumptions!)
• Variation in AK by factor of at least ~ 6 • Scatter around the average due to:
– Possible abundance variations– Multi-temperature plasma (DEM)– Preferential ‘tail’ contribution to lines
• Precise variations in AK can be studied only together with DEM accuracy of ~5% in absolute values for a particular spectrum.
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