Diagnosing the solar atmosphere through the Mg I b 5173 Å line. II. Morphological classification of the intensity and circular polarization profiles
arXiv:2503.12501 · doi:10.1051/0004-6361/202453232
Abstract
The Mg I b line at 5173 Å is primarily magnetically sensitive to heights between the mid photosphere and the low chromosphere, a region that has not been sufficiently explored in the solar atmosphere but is crucial for understanding the magnetic coupling between the two layers. New generation solar observatories are now performing polarimetric observations of this spectral line, enabling simultaneous measurements with multiple spectral lines. This allows for detailed studies of the magnetism around the temperature minimum region at high spatial, temporal, and spectral resolutions. We present a morphological classification of the Stokes and profiles of the Mg I b line using the Euclidean distance method on high spatial resolution observations from the Swedish 1-m Solar Telescope. The physical properties of the resulting classes were analyzed using classical inference methods. Additionally, we present a two-line full-Stokes inversion of the representative profiles in which the Mg I b line is treated fully under non-local thermodynamic equilibrium (NLTE) conditions, while the Fe I 6173 Å line is simultaneously inverted under LTE assumptions to provide photospheric constraints. This approach offers insights into the temperature stratification and other physical gradients involved in the formation of the different profile morphologies. We found nine classes of Stokes profiles and 16 classes of Stokes profiles in our Mg I b dataset. These classes can be further grouped into families based on shared characteristics, physical properties, and location. Our classification provides important information on the different environments and processes occurring in the solar atmosphere around the temperature minimum region. It is also relevant for improving the performance of NLTE inversions.
Paper accepted for publication in Section 9. The Sun and the Heliosphere of Astronomy and Astrophysics. 22 pages, 14 figures, 2 tables, 1 appendix
References in corpus (17)
- CRISPRED: A data pipeline for the CRISP imaging spectropolarimeter
- Emergence of small-scale magnetic loops through the quiet solar atmosphere
- The European Solar Telescope
- The origin of the reversed granulation in the solar photosphere
- Recovering Thermodynamics from Spectral Profiles observed by IRIS: A Machine and Deep Learning Approach
- Convection and the origin of Evershed flows in sunspot penumbrae
- Properties of solar plage from a spatially coupled inversion of Hinode SP data
- Two-dimensional spectroscopy of a sunspot. III Thermal and kinematic structure of the penumbra at 0.5"
- DeSIRe: Departure coefficient aided Stokes Inversion based on Response functions
- Determining the dynamics and magnetic fields in He I 10830 Å during a solar filament eruption
- Capabilities of bisector analysis of the Si I 10827 A line for estimating line-of-sight velocities in the quiet Sun
- Chromospheric polarimetry through multi-line observations of the 850 nm spectral region III: Chromospheric jets driven by twisted magnetic fields
- Shape-based clustering of synthetic Stokes profiles using k-means and k-Shape
- A modified Milne-Eddington approximation for a qualitative interpretation of chromospheric spectral lines
- Magnetic field inference from the spectral region around the Mg I line using the weak-field approximation
- Diagnosing the solar atmosphere through the Mg I b 5173 Å line. I. Nonlocal thermodynamic equilibrium inversions versus traditional inferences
- Formation and morphology of anomalous solar circular polarization