Investigating the capability to infer the magnetic field from non-local thermodynamic equilibrium inversions of the Mg I 12.32 μm line

¹ State Key Laboratory of Solar Activity and Space Weather, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
² School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
³ Solar Research Laboratory, National Research Institute of Astronomy and Geophysics, Helwan, Cairo 11421, Egypt
⁴ Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, China

^⋆ Corresponding author: xybai@bao.ac.cn

Received: 29 June 2025
Accepted: 11 August 2025

Abstract

We study the diagnostic potential of the Mg I 12.32 μm spectral line for probing solar magnetic fields through inversions of Stokes profiles derived from a three-dimensional magnetohydrodynamic (3D MHD) simulation. Using the STockholm inversion Code (STiC), we synthesized and inverted the Stokes profiles of the Mg I 12.32 μm from a Bifrost simulation, focusing on a region with diverse magnetic field strengths. Our analysis evaluates the accuracy of retrieved atmospheric parameters under varying noise levels. The minimum discrepancy between inferred and original atmospheres occurs at log (τ₅₀₀) =  − 2.9, aligning with the formation height of the Mg I 12.32 μm line. The results demonstrate robust temperature recovery even for a noise level of 1 × 10⁻² relative to the continuum intensity (I_c), while the magnetic field components exhibit strong agreement with the simulation for noise levels up to 1 × 10⁻³ I_c. This study highlights the Mg I 12.32 μm line’s utility in diagnosing solar magnetic fields, underscoring the importance of observations at high signal-to-noise ratios for future instruments.