S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 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)

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 RESIK - instant collection of spectra Bragg law: k λ =2d sinΘ Рентгеновский Спектрометр с Изогнутыми Кристаллами Measure spectra in range: nm – nm, instantly in all λ

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Well callibrated RESIK, RHESSI, and GOES Spectra: 2003 April 26 flare Brian Dennis & Ken Phillips

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Some example spectra from ~1000 reformatted

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Prompt analysis - isothermal approximation - T & EM #1 #4 T from #1/#4 flux ratio EM from T and #4 flux (CHIANTI atomic data) Dividing the photon flux by EM  spectrum per unit EM (10 44 cm -3 ) Group spectra according to T and take averages Continuum from T and EM Removing the continuum allows to study line fuxes

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Vicinity of K and Ar He-like triplets Lines + cont Lines K Ar G ratio G ratio

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Observed temperature dependence for K XVIII w Polynomial fit Excitation: Mewe Ion equil: Mazzotta A K = A K x 2 A K / 2 Line Flux above the continuum (area) divide by emission measure determined in the isothermal approximation

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Observed temperature dependence for Ar XVII w (S XV 1s 2 – 1s6p contribution removed) Polynomial fit Excitation: Mewe Ion equil: Mazzotta A Ar = A Ar x 1.4 A Ar 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

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Differences „by eye” A K < 1/3 average : 8 intense cases A K > 1.8 x average : 8 intense cases Similar T ~ 7 MK

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 relative line variability - T plots 4 K Ar FWHM= x 3.6 FWHM= x 2.2

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Does K/Ar ratio correlate with… NO ! C M

S R CS R C 35th COSPAR Scientific Commission E1.9 Paris, July 2004 Conclusions Regular temperature behaviour of line emissivities  experimental determination of emission functions (be aware of assumptions!) Variation in A K 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 A K can be studied only together with DEM  accuracy of ~5% in absolute values for a particular spectrum.