Issue |
A&A
Volume 508, Number 1, December II 2009
|
|
---|---|---|
Page(s) | 501 - 511 | |
Section | Atomic, molecular, and nuclear data | |
DOI | https://doi.org/10.1051/0004-6361/200913082 | |
Published online | 24 September 2009 |
Benchmarking atomic data for astrophysics: Fe VII and other cool lines observed by Hinode EIS
DAMTP, Centre for Mathematical Sciences, Wilberforce road Cambridge CB3 0WA, UK e-mail: GDelZanna@spd.aas.org
Received:
7
August
2009
Accepted:
11
September
2009
The EUV spectrum of
is reviewed, using new
rates for electron impact excitation, atomic structure calculations,
and experimental data.
In particular, solar observations of a sunspot loop spectrum
obtained from the
Hinode EUV Imaging Spectrometer (EIS) are used.
Previous line identifications, mostly based on
laboratory data, have been assessed.
Large discrepancies between observed and predicted line
intensities and wavelengths are found for the decays from the 3s2 3p5 3d3
configuration, which are strong EUV lines.
We ascribe these discrepancies to incorrect
line identifications. A number of new identifications are
proposed. With these, very good agreement between
theory and experimental data is found.
A few transitions, in particular from the 3s2 3p6 3d 4s configuration,
are observed for the first time, and are shown to
provide a new important diagnostic for measuring the
electron temperature in the solar transition region.
The temperatures obtained at the base of solar coronal loops
are found to be close to the temperature of maximum
abundance in ionization equilibrium (
K
).
The assessment of the
lines was done in
conjunction with an assessment of all the strongest cool
lines observed with EIS. This spectrum is rich in transition region lines.
Some new identifications
are presented, in particular for
. Most of the strongest
transitions are identified,
however a large number of lines still awaits firm identification.
Key words: atomic data / line: identification / Sun: transition region / techniques: spectroscopic
© ESO, 2009
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