He I vector magnetic field maps of a sunspot and its superpenumbral fine-structure

Abstract

Advanced inversions of high-resolution spectropolarimetric observations of the He I triplet at 1083 nm are used to generate unique maps of the chromospheric magnetic field vector across a sunspot and its superpenumbral canopy. The observations were acquired by the Facility Infrared Spectropolarimeter (FIRS) at the Dunn Solar Telescope (DST) on 29 January 2012. Multiple atmospheric models are employed in the inversions, as superpenumbral Stokes profiles are dominated by atomic-level polarization while sunspot profiles are Zeeman-dominated but also exhibit signatures perhaps induced by symmetry breaking effects of the radiation field incident on the chromospheric material. We derive the equilibrium magnetic structure of a sunspot in the chromosphere, and further show that the superpenumbral magnetic field does not appear finely structured, unlike the observed intensity structure. This suggests fibrils are not concentrations of magnetic flux but rather distinguished by individualized thermalization. We also directly compare our inverted values with a current-free extrapolation of the chromospheric field. With improved measurements in the future, the average shear angle between the inferred magnetic field and the potential field may offer a means to quantify the non-potentiality of the chromospheric magnetic field to study the onset of explosive solar phenomena.

Accepted for publication in Solar Physics

References in corpus (9)

• Dynamic Fibrils are driven by Magnetoacoustic Shocks
• Advanced Forward Modeling and Inversion of Stokes Profiles Resulting from the Joint Action of the Hanle and Zeeman Effects
• On the prevalence of small-scale twist in the solar chromosphere and transition region
• Physical Properties of a Sunspot Chromosphere with Umbral Flashes
• The Nature of Running Penumbral Waves Revealed
• He I Vector Magnetometry of Field Aligned Superpenumbral Fibrils
• The magnetic field configuration of a solar prominence inferred from spectropolarimetric observations in the He I 10830 A triplet
• Influence of atomic polarization and horizontal illumination on the Stokes profiles of the He I 10830 multiplet
• A three-dimensional view of the thermal structure in a super-penumbral canopy

Cited by in corpus (24)

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• The cause of spatial structure in solar He I 1083 nm multiplet images
• Magnetic field variations associated with umbral flashes and penumbral waves
• Inference of the chromospheric magnetic field configuration of solar plage using the Ca II 8542 Å line
• Spectropolarimetric analysis of an active region filament. I. Magnetic and dynamical properties from single component inversions
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• Automated Spatiotemporal Analysis of Fibrils and Coronal Rain using the Rolling Hough Transform
• Upper Chromospheric Magnetic Field of a Sunspot Penumbra: Observations of Fine Structure
• The problem of the height dependence of magnetic fields in sunspots
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• Shock Heating Energy of Umbral Flashes Measured with Integral Field Unit Spectroscopy
• Three-dimensional magnetic structure of a sunspot: comparison of the photosphere and upper chromosphere
• Transverse motions in sunspot super-penumbral fibrils
• Magnetic Structure of an Erupting Filament
• Three-dimensional magnetic field structure of a flux emerging region in the solar atmosphere
• Chromospheric magnetic field: A comparison of He I 10830 A observations with nonlinear force-free field extrapolation
• Temperature diagnostics of chromospheric fibrils
• Simultaneous spectropolarimetric observations in the H$\alpha$ and Ca II 8662 Å lines of an active region
• Super Penumbral Chromospheric Flare
• The dependence of the magnetism of a near-limb sunspot on height
• Thomson scattering above solar active regions and an ad-hoc polarization correction method for the emissive corona