Spectroscopic Diagnostics of the Non-Maxwellian kappa-distributions Using SDO/EVE Observations of the 2012 March 7 X-class Flare

0494688 - ASÚ 2019 RIV US eng J - Journal Article
Dzifčáková, Elena - Zemanová, Alena - Dudík, Jaroslav - Mackovjak, Šimon
Spectroscopic Diagnostics of the Non-Maxwellian kappa-distributions Using SDO/EVE Observations of the 2012 March 7 X-class Flare.
Astrophysical Journal. Roč. 853, č. 3 (2018), č. článku 158. ISSN 0004-637X. E-ISSN 1538-4357
R&D Projects: GA ČR(CZ) GA17-16447S; GA ČR(CZ) GA18-09072S
Institutional support: RVO:67985815
Keywords : data analysis * radiation mechanisms * non-thermal
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 5.580, year: 2018

Spectroscopic observations made by the Extreme Ultraviolet Variability Experiment (EVE) on board the Solar Dynamics Observatory (SDO) during the 2012 March 7 X5.4-class flare (SOL2012-03-07T00: 07) are analyzed for signatures of the non-Maxwellian kappa-distributions. Observed spectra were averaged over 1 minute to increase photon statistics in weaker lines and the pre-flare spectrum was subtracted. Synthetic line intensities for the.distributions are calculated using the KAPPA database. We find strong departures (kappa less than or similar to 2) during the early and impulsive phases of the flare, with subsequent thermalization of the flare plasma during the gradual phase. If the temperatures are diagnosed from a single line ratio, the results are strongly dependent on the value of kappa. For kappa =. 2, we find temperatures about a factor of two higher than the commonly used Maxwellian ones. The non-Maxwellian effects could also cause the temperatures diagnosed from line ratios and from the ratio of GOES X-ray channels to be different. Multithermal analysis reveals the plasma to be strongly multithermal at all times with flat DEMs. For lower kappa, the DEM kappa are shifted toward higher temperatures. The only parameter that is nearly independent of. is electron density, where we find log n(e) [cm(-3)]) approximate to 11.5 almost independently of time. We conclude that the nonMaxwellian effects are important and should be taken into account when analyzing solar flare observations, including spectroscopic and imaging ones.
Permanent Link: http://hdl.handle.net/11104/0287790