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Title: CORONIUM IN THE LABORATORY: MEASURING THE Fe XIV GREEN CORONAL LINE BY LASER SPECTROSCOPY

The green coronal line at 530.3 nm was first observed during the total solar eclipse of 1869. Once identified as emitted by Fe XIV, it became clear that this highly charged ion was typical for the range of temperatures found in coronal plasmas, stellar winds, outflows, and accretion disks. Under these conditions of high ionization, the strongest transitions are in the X-ray, extreme ultraviolet, and ultraviolet wavelength range, with only few optical lines. For these so-called forbidden coronal lines, only scarce laboratory data is available, and even advanced atomic theory codes cannot yet predict their wavelengths with the accuracy required for precise absolute velocity determinations of such plasmas. Here we report on a study of the Fe XIV line, a key coronal transition of a highly charged ion, using laser spectroscopy in an electron beam ion trap, obtaining the first laboratory measurement of 530.2801(4) nm for its rest wavelength. The result enables the determination of absolute line shifts and line broadenings in hot turbulent plasmas and astrophysical environments, with an error bar of only 0.24 km s{sup –1}. In addition, our measurement provides a much-needed benchmark for advanced atomic structure calculations, which are fundamental for astronomy.
Authors:
; ; ; ; ; ; ;  [1] ;  [2]
  1. Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
  2. Justus-Liebig-Univerität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany)
Publication Date:
OSTI Identifier:
22270805
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 776; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ACCURACY; ASTRONOMY; ASTROPHYSICS; BENCHMARKS; ECLIPSE; ELECTRON BEAMS; EMISSION SPECTRA; EXTREME ULTRAVIOLET RADIATION; IRON IONS; LASER SPECTROSCOPY; LINE BROADENING; MULTICHARGED IONS; PLASMA; STELLAR WINDS; SUN; WAVELENGTHS; X RADIATION