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.