Modeling the Mg I from the NUV to MIR. II. Testing stellar models

Abstract

Aims. We tested the new atomic model using atmospheric models of stars of different spectral types: the Sun (dG2), HD22049 (dK2, Epsilon Eridani), GJ 832 (dM2), and GJ 581 (dM3). Methods. We used new Breit-Pauli distorted-wave (DW) multiconfiguration calculations, which proved to be relevant for many transitions in the mid-infrared (MIR) range. The new atomic model of Mg I includes the following: i) recomputed ECS data through the DW method, including the superlevels. ii) For the nonlocal thermodynamic equilibrium (NLTE) population calculations, 5676 theoretical transitions were added (3001 term-to-term). iii) All of these improvements were studied in the Sun and the stars listed above. Results. The Mg distribution between ionization states for stars with different effective temperatures was compared. For the Sun and Epsilon Eridani, Mg II predominates with more than 95 %, while for GJ 832 and GJ 581, Mg I represents more than 72 % of the population. Moreover, in the latter stars, the amount of Mg forming molecules in their atmosphere is at least two orders of magnitude higher. Regarding the NLTE population, a noticeable lower variability in the departure coefficients was found, indicating a better population coupling for the new model. Comparing the synthetic spectrum calculated with the older and new Mg I atomic model, these results show minimal differences in the visible range but they are stronger in the IR for all of the stars. This aspect should be considered when using lines from this region as indicators. Nevertheless, some changes in the spectral type were found, also emphasizing the need to test the atomic models in different atmospheric conditions. The most noticeable changes occurred in the FUV and NUV, obtaining a higher flux for the new atomic model regardless of the spectral type.

References in corpus (21)

• Gaia Data Release 2. Summary of the contents and survey properties
• The SIMBAD astronomical database
• ESPRESSO@VLT -- On-sky performance and first results
• The MUSCLES Treasury Survey I: Motivation and Overview
• The Ultraviolet Radiation Environment Around M dwarf Exoplanet Host Stars
• The MUSCLES Treasury Survey III: X-ray to Infrared Spectra of 11 M and K Stars Hosting Planets
• The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems
• Stellar Diameters and Temperatures V. Eleven Newly Characterized Exoplanet Host Stars
• Astrophysical Parameters and Habitable Zone of the Exoplanet Hosting Star GJ 581
• Mg line formation in late-type stellar atmospheres: I. The model atom
• Metallicities of M Dwarf Planet Hosts from Spectral Synthesis
• Solar oxygen abundance
• Semi-empirical Modeling of the Photosphere, Chromosphere, Transition Region, and Corona of the M-dwarf Host Star GJ 832
• The FeH Wing-Ford Band in Spectra of M Stars
• NLTE line formation for Mg\ione\ and Mg\ii\ in atmospheres of B-A-F-G-K stars
• The Rotation-Activity Correlations in K and M dwarfs. I. Stellar parameters, compilations of $v\sin i$ and $P/\sin i$ for a large sample of late-K and M dwarfs
• Metallicity determination of M dwarfs - Expanded parameter range in metallicity and effective temperature
• Multi-instrumental view of magnetic fields and activity of $\epsilon$ Eridani with SPIRou, NARVAL, and TESS
• Inelastic e+Mg collision data and its impact on modelling stellar and supernova spectra
• Semi-Empirical Modeling of the Atmospheres of the M Dwarf Exoplanet Hosts GJ 832 and GJ 581
• Modeling the MgI from the NUV to MIR: I. The Solar Case

Cited by in corpus (1)

• Solar photospheric spectrum microvariability II. Observed relations to magnetic activity and radial-velocity modulation