Publication detail

The First Empirical Determination of the Fe10+ and Fe13+ Freeze-in Distances in the Solar Corona

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

English 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

en

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.

English 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

Released

01.06.2018

Publisher

IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND

Location

England

Pages from

105

Pages to

119

Pages count

14

URL

Documents

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",
  annote="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.",
  address="IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND",
  chapter="148885",
  doi="10.3847/1538-4357/aabfb7",
  howpublished="print",
  institution="IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND",
  number="2",
  volume="259",
  year="2018",
  month="june",
  pages="105--119",
  publisher="IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND",
  type="journal article in Web of Science"
}