Solar Flare Composition and Thermodynamics from RESIK X-ray Spectra

Abstract

Previous estimates of the solar flare abundances of Si, S, Cl, Ar, and K from the RESIK X-ray crystal spectrometer on board the CORONAS-F spacecraft were made on the assumption of isothermal X-ray emission. We investigate the effect on these estimates by relaxing this assumption and instead determining the differential emission measure (DEM) or thermal structure of the emitting plasma by re-analyzing RESIK data for a GOES class M1.0 flare on 2002 November~14 (SOL2002-11-14T22:26) for which there was good data coverage. The analysis method uses a maximum-likelihood (Withbroe--Sylwester) routine for evaluating the DEM. In a first step, called here AbuOpt, an optimized set of abundances of Si, S, Ar, and K is found that is consistent with the observed spectra. With these abundances, the differential emission measure evolution during the flare is found. The abundance optimization leads to revised abundances of silicon and sulfur in the flare plasma: $A(\mathrm{S})=6.94\pm 0.06$ and $A(\mathrm{Si})=7.56\pm 0.08$ (on a logarithmic scale with $A(\mathrm{H})=12$). Previously determined abundances of Ar, K, and Cl from an isothermal assumption are still the preferred values. During the flare's maximum phase, the X-ray-emitting plasma has a basically two-temperature structure, with the cooler plasma with approximately constant temperature (3--6~MK) and a hotter plasma with temperature $16-21$~MK. Using imaging data from the RHESSI hard X-ray spacecraft, the emission volume of the hot plasma is deduced from which lower limits of the electron density $N_e$ and the thermal content of the plasma are given.

arXiv comment7 figures

References in corpus (17)

• The chemical composition of the Sun
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• A new approach to analyzing solar coronal spectra and updated collisional ionization equilibrium calculations. II. Additional ionization rate coefficients
• A Unified Picture of the FIP and Inverse FIP Effects
• Establishing a Connection Between Active Region Outflows and the Solar Wind: Abundance Measurements with EIS/Hinode
• Non-WKB Models of the FIP Effect: Implications for Solar Coronal Heating and the Coronal Helium and Neon Abundances
• Non-WKB Models of the FIP Effect: The Role of Slow Mode Waves
• Plasma composition in a sigmoidal anemone active region
• Time-Dependent Density Diagnostics of Solar Flare Plasmas Using SDO/EVE
• The Coronal Abundance Anomalies of M Dwarfs
• Stellar Coronae, Solar Flares: a Detailed Comparison of sigma Gem, HR 1099, and the Sun in High-resolution X-rays
• The Solar Flare Chlorine Abundance from RESIK X-ray Spectra
• Highly Ionized Potassium Lines in Solar X-ray Spectra and the Abundance of Potassium
• The Solar Flare Sulphur Abundance from RESIK Observations
• The solar X-ray continuum measured by RESIK
• A solar spectroscopic absolute abundance of argon from RESIK
• Silicon abundance from RESIK solar flare observations

Cited by in corpus (18)

• The FIP and Inverse FIP Effects in Solar and Stellar Coronae
• Solar UV and X-Ray Spectral Diagnostics
• Solar Flare Element Abundances from the Solar Assembly for X-rays (SAX) on MESSENGER
• Solar X-ray Monitor On Board the Chandrayaan-2 Orbiter: In-flight Performance and Science Prospects
• The FIP and Inverse FIP Effects in Solar Flares
• Thermal and non-thermal emission from reconnecting twisted coronal loops
• Inverse FIP Effects in Giant Solar Flares Found from Earth X-Ray Albedo with Suzaku/XIS
• Determination of the total accelerated electron rate and power using solar flare hard X-ray spectra
• Soft X-ray emission in kink-unstable coronal loops
• RESIK Solar X-ray flare element abundances on a non-isothermal assumption
• Coronal Elemental Abundances during A-class Solar Flares Observed by Chandrayaan-2 XSM
• First Results for Solar Soft X-ray Irradiance Measurements from the Third Generation Miniature X-Ray Solar Spectrometer
• X-ray Flare Spectra from the DIOGENESS Spectrometer and its concept applied to ChemiX on the Interhelioprobe spacecraft
• Soft X-ray Spectral Diagnostics of Multi-thermal Plasma in Solar Flares with Chandrayaan-2 XSM
• Thermal characteristics and the differential emission measure distribution during a B8.3 flare on July 04, 2009
• Numerical calculation of ion runaway distributions
• On the Application of Differential Evolution to the Analysis of X-Ray Spectra
• Evolution of Elemental Abundances During B-Class Solar Flares: Soft X-ray Spectral Measurements with Chandrayaan-2 XSM