CHIANTI-AN ATOMIC DATABASE FOR EMISSION LINES. XI. EXTREME-ULTRAVIOLET EMISSION LINES OF Fe VII, Fe VIII, AND Fe IX OBSERVED BY HINODE/EIS

Journal Article · Thu Dec 10 04:00:00 EST 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/707/1/173· OSTI ID:21389314

Young, P R ^[1]; Landi, E ^[2]

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1. George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)
2. Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States)

A detailed study of emission lines from Fe VII, Fe VIII, and Fe IX observed by the EUV Imaging Spectrometer on board the Hinode satellite is presented. Spectra in the ranges 170-212 A and 246-292 A show strongly enhanced lines from the upper solar transition region (temperatures 5.4 <= log T <= 5.9) allowing a number of new line identifications to be made. Comparisons of Fe VII lines with predictions from a new atomic model reveal new plasma diagnostics, however there are a number of disagreements between theory and observation for emission line ratios insensitive to density and temperature, suggesting improved atomic data are required. Line ratios for Fe VIII also show discrepancies with theory, with the strong lambda185.21 and lambda186.60 lines underestimated by 60%-80% compared to lines between 192 and 198 A. A newly identified multiplet between 253.9 and 255.8 A offers excellent temperature diagnostic opportunities relative to the lines between 185 and 198 A, however the atomic model underestimates the strength of these lines by factors of 3-6. Two new line identifications are made for Fe IX at wavelengths 176.959 A and 177.594 A, while seven other lines between 186 and 200 A are suggested to be due to Fe IX but for which transition identifications cannot be made. The new atomic data for Fe VII and Fe IX are demonstrated to significantly modify models for the response function of the Transition Region And Coronal Explorer 195 A imaging channel, affecting temperature determinations from this channel. The data will also affect the response functions for other solar EUV imaging instruments such as SOHO/EIT, STEREO/EUVI, and the upcoming AIA instrument on the Solar Dynamics Observatory.

• OSTI ID: 21389314
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 707; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ATOMIC MODELS
COMPARATIVE EVALUATIONS
DENSITY
ELECTROMAGNETIC RADIATION
EMISSION
EVALUATION
EXTREME ULTRAVIOLET RADIATION
FORECASTING
FUNCTIONS
MAIN SEQUENCE STARS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
PHYSICAL PROPERTIES
PLASMA DIAGNOSTICS
RADIATIONS
RESPONSE FUNCTIONS
SATELLITES
SPECTRA
SPECTROMETERS
STARS
SUN
ULTRAVIOLET RADIATION
WAVELENGTHS