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Title: DERIVING PLASMA DENSITIES AND ELEMENTAL ABUNDANCES FROM SERTS DIFFERENTIAL EMISSION MEASURE ANALYSIS

We use high-resolution spectral emission line data obtained by the SERTS instrument during three rocket flights to demonstrate a new approach for constraining electron densities of solar active region plasma. We apply differential emission measure (DEM) forward-fitting techniques to characterize the multithermal solar plasma producing the observed EUV spectra, with constraints on the high-temperature plasma from the Yohkoh Soft X-ray Telescope. In this iterative process, we compare line intensities predicted by an input source distribution to observed line intensities for multiple iron ion species, and search a broad range of densities to optimize {chi}{sup 2} simultaneously for the many available density-sensitive lines. This produces a density weighted by the DEM, which appears to be useful for characterizing the bulk of the emitting plasma over a significant range of temperature. This 'DEM-weighted density' technique is complementary to the use of density-sensitive line ratios and less affected by uncertainties in atomic data and ionization fraction for any specific line. Once the DEM shape and the DEM-weighted density have been established from the iron lines, the relative elemental abundances can be determined for other lines in the spectrum. We have also identified spectral lines in the SERTS wavelength range that may be problematic.
Authors:
;  [1] ;  [2]
  1. Physics Department, University of Memphis, Memphis, TN 38152 (United States)
  2. Astronomy Department, University of Maryland, College Park, MD 20742 (United States)
Publication Date:
OSTI Identifier:
22092307
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 757; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; ELECTRON DENSITY; EMISSION SPECTRA; EXTREME ULTRAVIOLET RADIATION; EXTREME ULTRAVIOLET SPECTRA; GAMMA RADIATION; HOT PLASMA; IONIZATION; IRON; IRON IONS; ITERATIVE METHODS; PLASMA DENSITY; RESOLUTION; SOFT X RADIATION; SUN; TELESCOPES; ULTRAVIOLET RADIATION