Ca ii 854.2 nm in an enhanced network region simulated with MURaM-ChE
arXiv:2602.02851 · doi:10.1051/0004-6361/202556213
Abstract
The Ca ii 854.2 nm line is widely used to study the chromosphere of the Sun. In the quiet Sun, the spatially averaged line profile shows a red asymmetry and a redshift of the line center. It is known that the effect of isotopic splitting must be taken into account in the forward modeling to reproduce the observed asymmetry. So far, no numerical model could match an average observed line profile in terms of the line width and asymmetry. Our goal is to investigate how well a simulation computed with the chromospheric extension of the MURaM code (MURaM-ChE) reproduces the spatially averaged Ca ii 854.2 nm line profile. We aim to determine the contributions from the isotopic splitting versus the dynamics in the atmosphere to the resulting line width and asymmetry. We solve the radiative transfer problem three times, once considering only the most abundant isotope of calcium in the atmosphere, once taking six calcium isotopes into account, and finally using a single composite atom model. We find the forward modeled spatially and temporally averaged spectra to be in good agreement with an average observation of the quiet Sun. In order to match the observed line width, the simulated atmosphere must be sufficiently dynamic. The typical red asymmetry can only be reproduced by taking the isotopic splitting effect into account, as suggested in the literature.
arXiv comment12 pages, 8 figures, Accepted for publication in A&A
References in corpus (30)
- The chemical composition of the Sun
- The stellar atmosphere simulation code Bifrost
- CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
- Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
- Numerical simulation of the three-dimensional structure and dynamics of the non-magnetic solar chromosphere
- The formation of the Halpha line in the solar chromosphere
- Extension of the MURaM radiative MHD code for coronal simulations
- Approximations for radiative cooling and heating in the solar chromosphere
- A publicly available simulation of an enhanced network region of the Sun
- Non-equilibrium hydrogen ionization in 2D simulations of the solar atmosphere
- Radiative transfer with scattering for domain-decomposed 3D MHD simulations of cool stellar atmospheres
- RH 1.5D: a massively parallel code for multi-level radiative transfer with partial frequency redistribution and Zeeman polarisation
- The solar chromosphere at high resolution with IBIS. IV. Dual-line evidence of heating in chromospheric network
- 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
- Radiative diagnostics in the solar photosphere and chromosphere
- Spectropolarimetric capabilities of Ca II 8542 A line
- Partial redistribution in 3D non-LTE radiative transfer in solar atmosphere models
- Chromospheric Extension of the MURaM Code
- Non-equilibrium calcium ionisation in the solar atmosphere
- Time-dependent hydrogen ionisation in the solar chromosphere. I: Methods and first results
- The Hanle and Zeeman polarization signals of the solar Ca II 8542 Å line
- The effect of isotopic splitting on the bisector and inversions of the solar Ca II 854.2 nm line
- Sunrise III: Overview of Observatory and Instruments
- Numerical simulations and observations of Mg II in the solar chromosphere
- Quiet-Sun and Coronal Hole in \ion{Mg}{2}~k line as observed by IRIS
- Mg ii h&k spectra of an enhanced network region simulated with the MURaM-ChE code. Results using 1.5D synthesis
- Comparison of theoretical and observed Ca~{\sc ii}~8542 Stokes profiles in quiet regions at the centre of the solar disc
- Solar cycle variation in Sun-as-a-star Ca II 854.2 nm bisectors
- Structure and dynamics of the internetwork solar chromosphere: results of a small-scale dynamo simulation