TRANSITION REGION ABUNDANCE MEASUREMENTS DURING IMPULSIVE HEATING EVENTS

Journal Article · Fri Jun 10 04:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/824/1/56· OSTI ID:22666187

Warren, Harry P.; Doschek, George A. ^[1]; Brooks, David H. ^[2]; Feldman, Uri ^[3]

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1. Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
2. College of Science, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)
3. Artep, Inc., 2922 Excelsior Springs Court, Ellicott City, MD 21042 (United States)

It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona, low-FIP elements such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements such as C, N, O, Ar, and Ne. In this paper we report on measurements of plasma composition made during impulsive heating events observed at transition region temperatures with the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode . During these events the intensities of O iv, v, and vi emission lines are enhanced relative to emission lines from Mg v, vi, and vii and Si vi and vii, and indicate a composition close to that of the photosphere. Long-lived coronal fan structures, in contrast, show an enrichment of low-FIP elements. We conjecture that the plasma composition is an important signature of the coronal heating process, with impulsive heating leading to the evaporation of unfractionated material from the lower layers of the solar atmosphere and higher-frequency heating leading to long-lived structures and the accumulation of low-FIP elements in the corona.

• OSTI ID: 22666187
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 824; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
EMISSION
ENRICHMENT
EVAPORATION
EXTREME ULTRAVIOLET RADIATION
HIGH-FREQUENCY HEATING
IONIZATION POTENTIAL
LAYERS
PHOTOSPHERE
PLASMA
SOLAR CORONA
SPECTROMETERS