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Solar X-ray spectra from the RESIK crystal spectrometer on the {\em CORONAS-F} spacecraft (spectral range $3.3-6.1$~\AA) are analyzed for thirty-three flares using a method to derive abundances of Si, S, Ar, and K, emission lines of which…

Solar and Stellar Astrophysics · Physics 2015-05-27 B. Sylwester , K. J. H. Phillips , J. Sylwester , A. Kepa

The abundance of chlorine is determined from X-ray spectra obtained with the RESIK instrument on {\em CORONAS-F} during solar flares between 2002 and 2003. Using weak lines of He-like Cl, \ion{Cl}{16}, between 4.44 and 4.50 \AA, and with…

Solar and Stellar Astrophysics · Physics 2015-05-28 B. Sylwester , K. J. H. Phillips , J. Sylwester , V. D. Kuznetsov

The RESIK instrument on the CORONAS-F spacecraft obtained solar flare and active region X-ray spectra in four channels covering the wavelength range 3.8 -- 6.1 \AA in its operational period between 2001 and 2003. Several highly ionized…

Solar and Stellar Astrophysics · Physics 2015-06-12 B. Sylwester , K. J. H. Phillips , J. Sylwester , A. Kepa

The detailed knowledge of plasma heating and acceleration region properties presents a major observational challenge in solar flare physics. Using the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), the high temperature differential…

Solar and Stellar Astrophysics · Physics 2015-12-02 Natasha Jeffrey , Eduard Kontar , Brian Dennis

We use RHESSI high-resolution imaging and spectroscopy observations from ~6 to 100 keV to determine the statistical relationships between measured parameters (temperature, emission measure, etc.) of hot, thermal plasma in 37 intense (GOES…

Solar and Stellar Astrophysics · Physics 2014-06-25 Amir Caspi , Säm Krucker , R. P. Lin

Observations of He-like and H-like Ar (Ar XVII and Ar XVIII) lines at 3.949 Angstroms and 3.733 Angstroms respectively with the RESIK X-ray spectrometer on the CORONAS-F spacecraft, together with temperatures and emission measures from the…

Solar and Stellar Astrophysics · Physics 2015-05-19 J. Sylwester , B. Sylwester , K. J. H. Phillips , V. D. Kuznetsov

Spectroscopic observations in X-ray wavelengths provide excellent diagnostics of the temperature distribution in solar flare plasma. The Solar X-ray Monitor (XSM) onboard the Chandrayaan-2 mission provides broad-band disk integrated soft…

We report solar flare plasma to be multi-thermal in nature based on the theoretical model and study of the energy-dependent timing of thermal emission in ten M-class flares. We employ high-resolution X-ray spectra observed by the Si…

Solar and Stellar Astrophysics · Physics 2011-03-30 Rajmal Jain , Arun Kumar Awasthi , Arvind Singh Rajpurohit , Markus J. Aschwanden

We investigate the evolution of differential emission measure distribution (DEM[T]) in various phases of a B8.3 flare, which occurred on July 04, 2009. We analyze the soft X-ray (SXR) emission in 1.6-8.0 keV range, recorded collectively by…

Solar and Stellar Astrophysics · Physics 2016-06-08 Arun Kumar Awasthi , Barbara Sylwester , Janusz Sylwester , Rajmal Jain

Soft X-ray spectra 3.33 A - 6.15 A from the RESIK instrument on CORONAS-F constitute a unique database for the study of the physical conditions of solar flare plasmas, enabling the calculation of differential emission measures. The two…

Solar and Stellar Astrophysics · Physics 2020-10-14 A. Kepa , R. Falewicz , M. Siarkowski , M. Pietras

The Ar XVII X-ray line group principally due to transitions 1s2 - 1s2l (l=s, p) near 4 Anstroms was observed in numerous flares by the RESIK bent crystal spectrometer aboard CORONAS-F between 2001 and 2003. The three line features include…

Astrophysics · Physics 2009-11-13 J. Sylwester , B. Sylwester , K. J. H. Phillips

We test the compatibility and biases of multi-thermal flare DEM (differential emission measure) peak temperatures determined with AIA with those determined by GOES and RHESSI using the isothermal assumption. In a set of 149 M- and X-class…

Solar and Stellar Astrophysics · Physics 2015-06-18 Daniel F. Ryan , Aidan M. O'Flannagain , Markus J. Aschwanden , Peter T. Gallagher

The RESIK instrument on {\em CORONAS-F} spacecraft observed several sulphur X-ray lines in three of its four channels covering the wavelength range 3.8-6.1 \AA\ during solar flares. The fluxes are analyzed to give the sulphur abundance.…

Solar and Stellar Astrophysics · Physics 2015-06-04 J. Sylwester , B. Sylwester , K. J. H. Phillips , V. D. Kuznetsov

In previous works we have developed a method to convert solar X-ray data, collected with the Yohkoh/SXT, into templates of stellar coronal observations. Here we apply the method to several solar flares, for comparison with stellar X-ray…

Astrophysics · Physics 2009-11-06 F. Reale , G. Peres , S. Orlando

Using methods of differential evolution (DE,) we determined the coronal elemental abundances and the differential emission measure (DEM) distributions for the plasma flaring on 2003 January 21. The analyses have been based on RESIK X-ray…

Solar and Stellar Astrophysics · Physics 2022-03-09 Anna Kepa , Barbara Sylwester , Marek Siarkowski , Janusz Sylwester

The quiet-Sun X-ray emission is important for deducing coronal heating mechanisms, but it has not been studied in detail since the Orbiting Solar Observatory (OSO) spacecraft era. Bragg crystal spectrometer X-ray observations have generally…

Solar and Stellar Astrophysics · Physics 2015-05-18 B. Sylwester , J. Sylwester , K. J. H. Phillips

The calcium abundance in flare plasmas is estimated using X-ray spectra from the Solar Maximum Mission Bent Crystal Spectrometer (BCS) during the decays of 194 flares (GOES classifications from B6.4 to X13) occurring between 1980 and 1989.…

Solar and Stellar Astrophysics · Physics 2022-05-18 J. Sylwester , B. Sylwester , K. J. H. Phillips , A. Kepa

Deriving a well-constrained differential emission measure (DEM) distribution for solar flares has historically been difficult, primarily because no single instrument is sensitive to the full range of coronal temperatures observed in flares,…

Solar and Stellar Astrophysics · Physics 2014-06-25 Amir Caspi , James M. McTiernan , Harry P. Warren

In this paper we present the differential emission measures (DEMs) of two sub-A class microflares observed in hard X-rays (HXRs) by the FOXSI-2 sounding rocket experiment, on 2014 December 11. The second FOXSI (Focusing Optics X-ray Solar…

The solar X-ray continuum emission at five wavelengths between 3.495 Angstroms and 4.220 Angstroms for 19 flares in a seven-month period in 2002--2003 was observed by the RESIK crystal spectrometer on CORONAS-F. In this wavelength region,…

Solar and Stellar Astrophysics · Physics 2015-05-18 K. J. H. Phillips , J. Sylwester , B. Sylwester , V. D. Kuznetsov
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