Clustering Analysis of Ca i 4227 Line Polarization Using Magnetohydrodynamic Simulations of the Solar Atmosphere

The Ca i 4227 Å line is a strong resonance line formed in the solar chromosphere. At the limb, it produces the largest scattering polarization signal. So far, modeling the linear polarization in this line has been limited to the use of one-dimensional semiempirical models of the solar atmosphere. Us...

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Main Authors: Harsh Mathur, L. S. Anusha, Devang Agnihotri
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adbe76
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author Harsh Mathur
L. S. Anusha
Devang Agnihotri
author_facet Harsh Mathur
L. S. Anusha
Devang Agnihotri
author_sort Harsh Mathur
collection DOAJ
description The Ca i 4227 Å line is a strong resonance line formed in the solar chromosphere. At the limb, it produces the largest scattering polarization signal. So far, modeling the linear polarization in this line has been limited to the use of one-dimensional semiempirical models of the solar atmosphere. Using three-dimensional magnetohydrodynamical models of the solar atmosphere, in this paper, we perform 1.5D radiative transfer calculations to understand the formation of linear polarization profiles due to resonance scattering in this line at a near limb position. We focus on studying the sensitivity of the resonance scattering polarization to the temperature and the density structures in the atmosphere. We do not include the effects of magnetic and velocity fields in this study. We use clustering analysis to identify linear polarization profiles with similar shapes and group them accordingly for our study. We analyze the structure of the linear polarization profiles across 14 clusters, each representing different realizations of the solar atmosphere. Using source function ratio plots at various wing and core wavelength positions, we provide a qualitative explanation of linear polarization profiles in these clusters.
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spelling doaj-art-02ee68d8fe8049009ceedf0e4478321e2025-08-20T03:06:01ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198318410.3847/1538-4357/adbe76Clustering Analysis of Ca i 4227 Line Polarization Using Magnetohydrodynamic Simulations of the Solar AtmosphereHarsh Mathur0https://orcid.org/0000-0001-5253-4213L. S. Anusha1https://orcid.org/0000-0003-4928-2021Devang Agnihotri2https://orcid.org/0009-0003-8000-2179Indian Institute of Astrophysics , II Block, Koramangala, Bengaluru 560 034, India; University of Calcutta , College Street, Kolkata 700073, IndiaIndian Institute of Astrophysics , II Block, Koramangala, Bengaluru 560 034, India; Pondicherry University , R.V. Nagar, Kalapet, Pondicherry-605014, UT of Puducherry, IndiaIndian Institute of Astrophysics , II Block, Koramangala, Bengaluru 560 034, India; Pondicherry University , R.V. Nagar, Kalapet, Pondicherry-605014, UT of Puducherry, IndiaThe Ca i 4227 Å line is a strong resonance line formed in the solar chromosphere. At the limb, it produces the largest scattering polarization signal. So far, modeling the linear polarization in this line has been limited to the use of one-dimensional semiempirical models of the solar atmosphere. Using three-dimensional magnetohydrodynamical models of the solar atmosphere, in this paper, we perform 1.5D radiative transfer calculations to understand the formation of linear polarization profiles due to resonance scattering in this line at a near limb position. We focus on studying the sensitivity of the resonance scattering polarization to the temperature and the density structures in the atmosphere. We do not include the effects of magnetic and velocity fields in this study. We use clustering analysis to identify linear polarization profiles with similar shapes and group them accordingly for our study. We analyze the structure of the linear polarization profiles across 14 clusters, each representing different realizations of the solar atmosphere. Using source function ratio plots at various wing and core wavelength positions, we provide a qualitative explanation of linear polarization profiles in these clusters.https://doi.org/10.3847/1538-4357/adbe76Radiative transferSolar chromosphereClustering
spellingShingle Harsh Mathur
L. S. Anusha
Devang Agnihotri
Clustering Analysis of Ca i 4227 Line Polarization Using Magnetohydrodynamic Simulations of the Solar Atmosphere
The Astrophysical Journal
Radiative transfer
Solar chromosphere
Clustering
title Clustering Analysis of Ca i 4227 Line Polarization Using Magnetohydrodynamic Simulations of the Solar Atmosphere
title_full Clustering Analysis of Ca i 4227 Line Polarization Using Magnetohydrodynamic Simulations of the Solar Atmosphere
title_fullStr Clustering Analysis of Ca i 4227 Line Polarization Using Magnetohydrodynamic Simulations of the Solar Atmosphere
title_full_unstemmed Clustering Analysis of Ca i 4227 Line Polarization Using Magnetohydrodynamic Simulations of the Solar Atmosphere
title_short Clustering Analysis of Ca i 4227 Line Polarization Using Magnetohydrodynamic Simulations of the Solar Atmosphere
title_sort clustering analysis of ca i 4227 line polarization using magnetohydrodynamic simulations of the solar atmosphere
topic Radiative transfer
Solar chromosphere
Clustering
url https://doi.org/10.3847/1538-4357/adbe76
work_keys_str_mv AT harshmathur clusteringanalysisofcai4227linepolarizationusingmagnetohydrodynamicsimulationsofthesolaratmosphere
AT lsanusha clusteringanalysisofcai4227linepolarizationusingmagnetohydrodynamicsimulationsofthesolaratmosphere
AT devangagnihotri clusteringanalysisofcai4227linepolarizationusingmagnetohydrodynamicsimulationsofthesolaratmosphere