Using multi-line spectropolarimetric observations of forbidden emission lines to measure single-point coronal magnetic fields

Abstract

Polarized magnetic dipole (M1) emission lines provide important diagnostics for the magnetic field dominating the evolution of the solar corona. This paper advances a multi-line technique using specific combinations of M1 lines to infer the full vector magnetic field for regions of optically thin emission that can be localized along a given line of sight. Our analytical formalism is a generalization of the "single-point inversion" approach introduced by Plowman. We show that combinations of M1 transitions for which each is either a $J=1\to 0$ transition or has equal Landé g-factors for the upper and lower levels contain degenerate spectropolarimetric information that prohibits the application of the single-point inversion technique. This may include the pair of infrared Fe XIII lines discussed by Plowman. We identify the Fe XIII 1074.7 nm and Si X 1430.1 nm lines as one alternative combination for implementing this technique. Our sensitivity analysis, based on coronal loop properties, suggests that for photon noise levels around $10^{-4}$ of the line intensity, which will be achievable with the National Science Foundation's Daniel K. Inouye Solar Telescope, magnetic fields with sufficient strength ($\sim 10$ G) and not severely inclined to the line-of-sight ($\lesssim 35^{\circ }$) can be recovered with this method. Degenerate solutions exist; though, we discuss how added constraints may help resolve them or reduce their number.

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Cited by in corpus (6)

• Mapping the Sun's coronal magnetic field using the Zeeman effect
• On single-point inversions of magnetic dipole lines in the corona
• A spectroscopic survey of infrared 1-4μm spectra in regions of prominent solar coronal emission lines of Fe XIII, Si X, and Si IX
• Magnetic Energy Powers the Corona: How We Can Understand its 3D Storage & Release
• Reconstruction of Coronal Magnetic Fields Using a Poloidal-Toroidal Representation
• Efficient and Automated Inversions of Magnetically-Sensitive Forbidden Coronal Lines: CLEDB -- The Coronal Line Emission DataBase Magnetic Field Inversion Algorithm