Study of the polarization produced by the Zeeman effect in the solar Mg I b lines

Abstract

The next generation of solar observatories aim to understand the magnetism of the solar chromosphere. Therefore, it is crucial to understand the polarimetric signatures of chromospheric spectral lines. For this purpose, we here examine the suitability of the three Fraunhofer Mg I b1, b2, and b4 lines at 5183.6, 5172.7, and 5167.3 A, respectively. We start by describing a simplified atomic model of only 6 levels and 3 line transitions for computing the atomic populations of the 3p-4s (multiplet number 2) levels involved in the Mg I b line transitions assuming non-local thermodynamic conditions and considering only the Zeeman effect using the field-free approximation. We test this simplified atom against more complex ones finding that, although there are differences in the computed profiles, they are small compared with the advantages provided by the simple atom in terms of speed and robustness. After comparing the three Mg I lines, we conclude that the most capable one is the b2 line as b1 forms at similar heights and always show weaker polarization signals while b4 is severely blended with photospheric lines. We also compare Mg I b2 with the K I D1 and Ca II 8542 A lines finding that the former is sensitive to the atmospheric parameters at heights that are in between those covered by the latter two lines. This makes Mg I b2 an excellent candidate for future multi-line observations that aim to seamlessly infer the thermal and magnetic properties of different features in the lower solar atmosphere.

arXiv comment14 pages, 11 figures, and 5 tables

References in corpus (34)

• The chemical composition of the Sun
• The stellar atmosphere simulation code Bifrost
• Sunrise: instrument, mission, data and first results
• The Imaging Magnetograph eXperiment (IMaX) for the Sunrise balloon-borne solar observatory
• The Sunrise Mission
• A publicly available simulation of an enhanced network region of the Sun
• An Open Source, Massively Parallel Code for Non-LTE Synthesis and Inversion of Spectral Lines and Zeeman-induced Stokes Profiles
• Magnetic Structure of Sunspots
• Emergence of small-scale magnetic loops through the quiet solar atmosphere
• The solar chromosphere at high resolution with IBIS. I. New insights from the Ca II 854.2 nm line
• The second flight of the SUNRISE balloon-borne solar observatory: overview of instrument updates, the flight, the data and first results
• The Filter Imager SuFI and the Image Stabilization and Light Distribution System ISLiD of the Sunrise Balloon-Borne Observatory: Instrument Description
• The Wave-Front Correction System for the Sunrise Balloon-Borne Solar Observatory
• Non-LTE inversions of the Mg II h&k and UV triplet lines
• Three-dimensional non-LTE radiative transfer computation of the Ca 8542 infrared line from a radiation-MHD simulation
• Non-local thermodynamic equilibrium inversions from a 3D MHD chromospheric model
• Spectropolarimetric capabilities of Ca II 8542 A line
• Three-dimensional modeling of the Ca II H&K lines in the solar atmosphere
• Spectropolarimetric NLTE inversion code SNAPI
• The quiet solar atmosphere observed and simulated in NaD1
• Partial redistribution in 3D non-LTE radiative transfer in solar atmosphere models
• Internetwork magnetic field distribution from simultaneous 1.56 micron and 630 nm observations
• Three-dimensional radiative transfer simulations of the scattering polarization of the hydrogen Ly$\alpha$ line in a MHD model of the chromosphere-corona transition region
• The Hanle and Zeeman polarization signals of the solar Ca II 8542 Å line
• Chromospheric polarimetry through multi-line observations of the 850 nm spectral region
• Quiet-Sun imaging asymmetries in NaI D1 compared with other strong Fraunhofer lines
• Ellerman bombs at high resolution. IV. Visibility in Na I and Mg I
• Solar polarimetry through the K I lines at 770 nm
• Chromospheric polarimetry through multi-line observations of the 850 nm spectral region II: A magnetic flux tube scenario
• A key physical mechanism for understanding the enigmatic linear polarization of the solar BaII and NaI D1 lines
• Numerical non-LTE 3D radiative transfer using a multigrid method
• Radiative transfer modeling of the enigmatic scattering polarization in the solar NaI D1 line
• Solar polarimetry in the K I $D_2$ line: A novel possibility for a stratospheric balloon
• On the Doppler Shift and Asymmetry of Stokes Profiles of Photospheric FeI and Chromospheric MgI Lines

Cited by in corpus (10)

• STiC -- A multi-atom non-LTE PRD inversion code for full-Stokes solar observations
• Diagnostic capabilities of spectropolarimetric observations for understanding solar phenomena I. Zeeman-sensitive photospheric lines
• The Sunrise Chromospheric Infrared Spectro-Polarimeter SCIP: an instrument for SUNRISE III
• A modified Milne-Eddington approximation for a qualitative interpretation of chromospheric spectral lines
• Magnetic field inference from the spectral region around the Mg I $b_2$ line using the weak-field approximation
• Stratification of canopy magnetic fields in a plage region. Constraints from a spatially-regularized weak-field approximation method
• Diagnosing the solar atmosphere through the Mg I b${}_2$ 5173 Å line. II. Morphological classification of the intensity and circular polarization profiles
• Non-Local Thermodynamic Equilibrium inversions of the Si I 10827 A spectral line
• Episodic Plasma Flows and Coronal Brightenings in an Arch Filament System Observed with SUNRISE III
• Asymmetry of Lines in the Spectra of the Sun and Solar-Type Stars