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BOE, B. HABBAL, S. DRUCKMÜLLER, M. LANDI, E. KOURKCHI, E. DING, A. ŠTARHA, P. HUTTON, J.
Original Title
The First Empirical Determination of the Fe10+ and Fe13+ Freeze-in Distances in the Solar Corona
Type
journal article in Web of Science
Language
English
Original Abstract
Heavy ions are markers of the physical processes responsible for the density and temperature distribution throughout the fine-scale magnetic structures that define the shape of the solar corona. One of their properties, whose empirical determination has remained elusive, is the "freeze-in" distance (R-f) where they reach fixed ionization states that are adhered to during their expansion with the solar wind. We present the first empirical inference of R-f for Fe10+ and Fe13+ derived from multi-wavelength imaging observations of the corresponding Fe XI (Fe10+) 789.2 nm and Fe XIV (Fe13+) 530.3 nm emission acquired during the 2015 March 20 total solar eclipse. We find that the two ions freeze-in at different heliocentric distances. In polar coronal holes (CHs)R-f is around 1.45 R-circle dot for Fe10+ and below 1.25 R-circle dot for Fe13+. Along open field lines in streamer regions, R-f ranges from 1.4 to 2 R-circle dot for Fe10+ and from 1.5 to 2.2 R-circle dot for Fe13+. These first empirical R-f values: (1) reflect the differing plasma parameters between CHs and streamers and structures within them, including prominences and coronal mass ejections; (2) are well below the currently quoted values derived from empirical model studies; and (3) place doubt on the reliability of plasma diagnostics based on the assumption of ionization equilibrium beyond 1.2 R-circle dot.
Keywords
Sun, corona, solar wind, eclipse, coronal mass ejection, particle emission
Authors
BOE, B.; HABBAL, S.; DRUCKMÜLLER, M.; LANDI, E.; KOURKCHI, E.; DING, A.; ŠTARHA, P.; HUTTON, J.
Released
1. 6. 2018
Publisher
IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Location
England
ISBN
0004-637X
Periodical
ASTROPHYSICAL JOURNAL
Year of study
259
Number
2
State
United States of America
Pages from
105
Pages to
119
Pages count
14
URL
http://iopscience.iop.org/article/10.3847/1538-4357/aabfb7/pdf
BibTex
@article{BUT148885, author="Benjamin {Boe} and Shadia Rifai {Habbal} and Miloslav {Druckmüller} and Enrico {Landi} and Ehsan {Kourkchi} and Adalbert {Ding} and Pavel {Štarha} and Joseph {Hutton}", title="The First Empirical Determination of the Fe10+ and Fe13+ Freeze-in Distances in the Solar Corona", journal="ASTROPHYSICAL JOURNAL", year="2018", volume="259", number="2", pages="105--119", doi="10.3847/1538-4357/aabfb7", issn="0004-637X", url="http://iopscience.iop.org/article/10.3847/1538-4357/aabfb7/pdf" }