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Title: ANOMALOUS RELATIVE AR/CA CORONAL ABUNDANCES OBSERVED BY THE HINODE/EUV IMAGING SPECTROMETER NEAR SUNSPOTS

In determining the element abundance of argon (a high first ionization potential; FIP element) relative to calcium (a low FIP element) in flares, unexpectedly high intensities of two Ar xiv lines (194.40, 187.96 Å) relative to a Ca xiv line (193.87 Å) intensity were found in small (a few arcseconds) regions near sunspots in flare spectra recorded by the Extreme-ultraviolet Imaging Spectrometer on the Hinode spacecraft. In the most extreme case the Ar xiv line intensity relative to the Ca xiv intensity was 7 times the value expected from the photospheric abundance ratio, which is about 30 times the abundance of argon relative to calcium in active regions, i.e., the measured Ar/Ca abundance ratio is about 10 instead of 0.37 as in active regions. The Ar xiv and Ca xiv lines are formed near 3.4 MK and have very similar contribution functions. This is the first observation of the inverse FIP effect in the Sun. Other regions show increases of 2–3 over photospheric abundances, or just photospheric abundances. This phenomenon appears to occur rarely and only over small areas of flares away from the regions containing multi-million degree plasma, but more work is needed to quantify the occurrences and theirmore » locations. In the bright hot regions of flares the Ar/Ca abundance ratio is coronal, i.e., the same as in active regions. In this Letter we show three examples of the inverse FIP effect.« less
Authors:
;  [1] ;  [2]
  1. Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
  2. Artep, Inc., 2922 Excelsior Springs Court, Ellicott City, MD 21042 (United States)
Publication Date:
OSTI Identifier:
22518932
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 808; 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; ARGON; CALCIUM; ELEMENT ABUNDANCE; EXTREME ULTRAVIOLET RADIATION; IONIZATION POTENTIAL; PHOTOSPHERE; PLASMA; SPACE VEHICLES; SUN; SUNSPOTS