Multilobed Stokes V Profiles of the Fe i 407.17 nm Line Observed by Sunrise iii

Abstract The near-ultraviolet part of the solar spectrum is densely crowded with spectral lines. Scattered among them are neutral iron lines with bell-shaped intensity profiles forming as high as the mid-chromosphere. Based on 1D model atmospheres, we predicted in our previous paper that these lines have unique multilobed Stokes V profiles even in the absence of gradients in magnetic field inclination or in line-of-sight velocity. The Sunrise Ultraviolet Spectropolarimeter and Imager (SUSI) instrument on board the Sunrise iii flight captured high spectral and spatial resolution observations in one such strong chromospheric Fe i line at 407.17 nm, in and around a sunspot. In these observations, these multilobed V profiles are best seen in the inner parts of the penumbra, where the Stokes V signal is strong and the Stokes I line shape displays the characteristic flattening of the inner wing along with a steep line core. By applying the weak field approximation (WFA) separately to the line core and wings, we infer line-of-sight magnetic field strengths ( B LOS ) at different heights in the atmosphere. We find differences between the inferred B LOS obtained from the line core and wing of up to 700 G. Despite the blend line in the blue wing and the relatively weak Stokes V signals, we show that it is still possible to qualitatively infer B LOS simultaneously at different heights in the atmosphere using the WFA on the Fe i 407.17 nm line.

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Journal
The Astrophysical Journal Letters
Published
2026-11-06
DOI
https://doi.org/10.3847/2041-8213/aeb5fe
Primary Topic
Solar and Space Plasma Dynamics
Type
article
Field-Weighted Citation Impact
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article

Multilobed Stokes V Profiles of the Fe i 407.17 nm Line Observed by Sunrise iii

A. Álvarez‐Herrero, A. L. Siu-Tapia, Takayoshi Oba, D. Orozco Suárez et al.
The Astrophysical Journal Letters
Solar and Space Plasma Dynamics
article

Multilobed Stokes V Profiles of the Fe i 407.17 nm Line Observed by Sunrise iii

A. Álvarez‐Herrero, A. L. Siu-Tapia, Takayoshi Oba, D. Orozco Suárez, J. C. del Toro Iniesta, J. S. Castellanos Durán, Ryohtaroh T. Ishikawa, T. L. Riethmüller, A. Lagg, Masahito Kubo, Damien Przybylski, Thomas Berkefeld, Sami Khan Solanki, Takuma Matsumoto, P. N. Bernasconi, Yukio Katsukawa, V. Martı́nez Pillet, Yusuke Kawabata, F. J. Bailén, J. Blanco Rodríguez, H. Strecker, B. Grauf, F. A. Iglesias, Achim M. Gandorfer, Johannes Hölken, Dušan Vukadinović, Alex J. Feller, H. N. Smitha, Edvarda Harnes, Alexander Bell, Michael Carpenter
article en

Abstract

Abstract The near-ultraviolet part of the solar spectrum is densely crowded with spectral lines. Scattered among them are neutral iron lines with bell-shaped intensity profiles forming as high as the mid-chromosphere. Based on 1D model atmospheres, we predicted in our previous paper that these lines have unique multilobed Stokes V profiles even in the absence of gradients in magnetic field inclination or in line-of-sight velocity. The Sunrise Ultraviolet Spectropolarimeter and Imager (SUSI) instrument on board the Sunrise iii flight captured high spectral and spatial resolution observations in one such strong chromospheric Fe i line at 407.17 nm, in and around a sunspot. In these observations, these multilobed V profiles are best seen in the inner parts of the penumbra, where the Stokes V signal is strong and the Stokes I line shape displays the characteristic flattening of the inner wing along with a steep line core. By applying the weak field approximation (WFA) separately to the line core and wings, we infer line-of-sight magnetic field strengths ( B LOS ) at different heights in the atmosphere. We find differences between the inferred B LOS obtained from the line core and wing of up to 700 G. Despite the blend line in the blue wing and the relatively weak Stokes V signals, we show that it is still possible to qualitatively infer B LOS simultaneously at different heights in the atmosphere using the WFA on the Fe i 407.17 nm line.

The Astrophysical Journal LettersVol. 1011(2)
University of Mendoza (AR), Kanazawa University (JP), University of Graz (AT), Universidad de La Laguna (ES), Universitat de València (ES), The Graduate University for Advanced Studies, SOKENDAI (JP), Institut für Sonnenphysik (DE), Johns Hopkins University Applied Physics Laboratory (US), National Institute for Fusion Science (JP), Max Planck Institute for Solar System Research (DE), Instituto Nacional de Técnica Aeroespacial (ES), Instituto de Astrofísica de Canarias (ES), Instituto de Astrofísica de Andalucía (ES), National Astronomical Observatory of Japan (JP), Nagoya University (JP), University of Göttingen (DE), The University of Tokyo (JP)
National Aeronautics and Space Administration, International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Max-Planck-Förderstiftung, European Commission, Deutsches Zentrum für Luft- und Raumfahrt, Georg-August-Universität Göttingen, Ministerio de Ciencia e Innovación, Technische Universität Braunschweig, International Max Planck Research School for Advanced Methods in Process and Systems Engineering, Instituto de Astrofísica de Andalucía, Japan Society for the Promotion of Science, Japan Aerospace Exploration Agency, European Regional Development Fund, Agencia Estatal de Investigación
Openalex Percentile: Top 26%
Solar and Space Plasma Dynamics
DOIOpen Access PDFOpenAlex
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