Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

ATOMIC-LEVEL PSEUDO-DEGENERACY of ATOMIC LEVELS GIVING TRANSITIONS INDUCED by MAGNETIC FIELDS, of IMPORTANCE for DETERMINING the FIELD STRENGTHS in the SOLAR CORONA

Li, Wenxian ; Yang, Yang ; Tu, Bingsheng ; Xiao, Jun ; Grumer, Jon LU ; Brage, Tomas LU ; Watanabe, Tetsuya ; Hutton, Roger LU and Zou, Yaming (2016) In Astrophysical Journal 826(2).
Abstract

We present a measured value for the degree of pseudo-degeneracy between two fine-structure levels in Fe9+ from line intensity ratios involving a transition induced by an external magnetic field. The extracted fine-structure energy difference between 3p4 3d 4D7/2 the and 4D7/2 levels, where the latter is the upper state for the magnetic-field induced line, is needed in our recently proposed method to measure magnetic-field strengths in the solar corona. The intensity of the 3p4 3d 4D7/2 → 3p5 2 P3/2 line at 257.262 Å is sensitive to the magnetic field external to the ion. This sensitivity is in turn strongly... (More)

We present a measured value for the degree of pseudo-degeneracy between two fine-structure levels in Fe9+ from line intensity ratios involving a transition induced by an external magnetic field. The extracted fine-structure energy difference between 3p4 3d 4D7/2 the and 4D7/2 levels, where the latter is the upper state for the magnetic-field induced line, is needed in our recently proposed method to measure magnetic-field strengths in the solar corona. The intensity of the 3p4 3d 4D7/2 → 3p5 2 P3/2 line at 257.262 Å is sensitive to the magnetic field external to the ion. This sensitivity is in turn strongly dependent on the energy separation in the pseudo-degeneracy through the mixing induced by the external magnetic field. Our measurement, which uses an Electron Beam Ion Trap with a known magnetic-field strength, indicates that this energy difference is 3.5 cm-1. The high abundance of Fe9+ and the sensitivity of the line's transition probability to field strengths below 0.1 T opens up the possibility of diagnosing coronal magnetic fields. We propose a new method to measure the magnetic field in the solar corona, from similar intensity ratios in Fe9+. In addition, the proposed method to use the line ratio of the blended line 3p4 3d 4D7/2.5/2 → 3p5 2P3/2 with another line from Fe x as the density diagnostic should evaluate the effect of the magnetic-field-induced transition line.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
atomic processes, magnetic fields, Sun: corona, techniques: spectroscopic, UV radiation
in
Astrophysical Journal
volume
826
issue
2
article number
219
publisher
American Astronomical Society
external identifiers
  • scopus:84982199292
  • wos:000381977900119
ISSN
0004-637X
DOI
10.3847/0004-637X/826/2/219
language
English
LU publication?
yes
id
485f3203-f07e-41f6-8df8-276420ce768a
date added to LUP
2016-09-20 22:57:02
date last changed
2024-04-19 08:55:48
@article{485f3203-f07e-41f6-8df8-276420ce768a,
  abstract     = {{<p>We present a measured value for the degree of pseudo-degeneracy between two fine-structure levels in Fe<sup>9+</sup> from line intensity ratios involving a transition induced by an external magnetic field. The extracted fine-structure energy difference between 3p<sup>4</sup> 3d <sup>4</sup>D<sub>7/2</sub> the and <sup>4</sup>D<sub>7/2</sub> levels, where the latter is the upper state for the magnetic-field induced line, is needed in our recently proposed method to measure magnetic-field strengths in the solar corona. The intensity of the 3p<sup>4</sup> 3d <sup>4</sup>D<sub>7/2</sub> → 3p<sup>5</sup> <sup>2</sup> P<sub>3/2</sub> line at 257.262 Å is sensitive to the magnetic field external to the ion. This sensitivity is in turn strongly dependent on the energy separation in the pseudo-degeneracy through the mixing induced by the external magnetic field. Our measurement, which uses an Electron Beam Ion Trap with a known magnetic-field strength, indicates that this energy difference is 3.5 cm<sup>-1</sup>. The high abundance of Fe<sup>9+</sup> and the sensitivity of the line's transition probability to field strengths below 0.1 T opens up the possibility of diagnosing coronal magnetic fields. We propose a new method to measure the magnetic field in the solar corona, from similar intensity ratios in Fe<sup>9+</sup>. In addition, the proposed method to use the line ratio of the blended line 3p<sup>4</sup> 3d <sup>4</sup>D<sub>7/2.5/2</sub> → 3p<sup>5</sup> <sup>2</sup>P<sub>3/2</sub> with another line from Fe x as the density diagnostic should evaluate the effect of the magnetic-field-induced transition line.</p>}},
  author       = {{Li, Wenxian and Yang, Yang and Tu, Bingsheng and Xiao, Jun and Grumer, Jon and Brage, Tomas and Watanabe, Tetsuya and Hutton, Roger and Zou, Yaming}},
  issn         = {{0004-637X}},
  keywords     = {{atomic processes; magnetic fields; Sun: corona; techniques: spectroscopic; UV radiation}},
  language     = {{eng}},
  month        = {{08}},
  number       = {{2}},
  publisher    = {{American Astronomical Society}},
  series       = {{Astrophysical Journal}},
  title        = {{ATOMIC-LEVEL PSEUDO-DEGENERACY of ATOMIC LEVELS GIVING TRANSITIONS INDUCED by MAGNETIC FIELDS, of IMPORTANCE for DETERMINING the FIELD STRENGTHS in the SOLAR CORONA}},
  url          = {{http://dx.doi.org/10.3847/0004-637X/826/2/219}},
  doi          = {{10.3847/0004-637X/826/2/219}},
  volume       = {{826}},
  year         = {{2016}},
}