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Title: Polarization of Coronal Forbidden Lines

Abstract

Since the magnetic field is responsible for most manifestations of solar activity, one of the most challenging problems in solar physics is the diagnostics of solar magnetic fields, particularly in the outer atmosphere. To this end, it is important to develop rigorous diagnostic tools to interpret polarimetric observations in suitable spectral lines. This paper is devoted to analyzing the diagnostic content of linear polarization imaging observations in coronal forbidden lines. Although this technique is restricted to off-limb observations, it represents a significant tool to diagnose the magnetic field structure in the solar corona, where the magnetic field is intrinsically weak and still poorly known. We adopt the quantum theory of polarized line formation developed in the framework of the density matrix formalism, and synthesize images of the emergent linear polarization signal in coronal forbidden lines using potential-field source-surface magnetic field models. The influence of electronic collisions, active regions, and Thomson scattering on the linear polarization of coronal forbidden lines is also examined. It is found that active regions and Thomson scattering are capable of conspicuously influencing the orientation of the linear polarization. These effects have to be carefully taken into account to increase the accuracy of the field diagnostics. Wemore » also found that linear polarization observation in suitable lines can give valuable information on the long-term evolution of the magnetic field in the solar corona.« less

Authors:
;  [1];  [2]
  1. Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan 650011 (China)
  2. Dipartimento di Astronomia e Scienza dello Spazio, Università di Firenze, Largo E. Fermi 2, I-50125 Firenze (Italy)
Publication Date:
OSTI Identifier:
22661223
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 838; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; COLLISIONS; DENSITY; DENSITY MATRIX; LIMBS; MAGNETIC FIELDS; POLARIZATION; SOLAR ACTIVITY; SOLAR CORONA; SUN; SURFACES; THOMSON SCATTERING

Citation Formats

Li, Hao, Qu, Zhongquan, and Landi Degl’Innocenti, Egidio, E-mail: sayahoro@ynao.ac.cn. Polarization of Coronal Forbidden Lines. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6625.
Li, Hao, Qu, Zhongquan, & Landi Degl’Innocenti, Egidio, E-mail: sayahoro@ynao.ac.cn. Polarization of Coronal Forbidden Lines. United States. doi:10.3847/1538-4357/AA6625.
Li, Hao, Qu, Zhongquan, and Landi Degl’Innocenti, Egidio, E-mail: sayahoro@ynao.ac.cn. Mon . "Polarization of Coronal Forbidden Lines". United States. doi:10.3847/1538-4357/AA6625.
@article{osti_22661223,
title = {Polarization of Coronal Forbidden Lines},
author = {Li, Hao and Qu, Zhongquan and Landi Degl’Innocenti, Egidio, E-mail: sayahoro@ynao.ac.cn},
abstractNote = {Since the magnetic field is responsible for most manifestations of solar activity, one of the most challenging problems in solar physics is the diagnostics of solar magnetic fields, particularly in the outer atmosphere. To this end, it is important to develop rigorous diagnostic tools to interpret polarimetric observations in suitable spectral lines. This paper is devoted to analyzing the diagnostic content of linear polarization imaging observations in coronal forbidden lines. Although this technique is restricted to off-limb observations, it represents a significant tool to diagnose the magnetic field structure in the solar corona, where the magnetic field is intrinsically weak and still poorly known. We adopt the quantum theory of polarized line formation developed in the framework of the density matrix formalism, and synthesize images of the emergent linear polarization signal in coronal forbidden lines using potential-field source-surface magnetic field models. The influence of electronic collisions, active regions, and Thomson scattering on the linear polarization of coronal forbidden lines is also examined. It is found that active regions and Thomson scattering are capable of conspicuously influencing the orientation of the linear polarization. These effects have to be carefully taken into account to increase the accuracy of the field diagnostics. We also found that linear polarization observation in suitable lines can give valuable information on the long-term evolution of the magnetic field in the solar corona.},
doi = {10.3847/1538-4357/AA6625},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 838,
place = {United States},
year = {2017},
month = {3}
}