Can we trust elemental abundances derived in late-type giants with the classical 1D stellar atmosphere models?

TL;DR

This study compares 3D hydrodynamical and classical 1D stellar atmosphere models for late-type giants, finding small differences for neutral atoms but significant potential discrepancies for ions, especially at higher excitation potentials.

Contribution

It provides a detailed comparison of 3D and 1D abundance derivations in late-type giants, highlighting conditions where 1D models are reliable or may lead to inaccuracies.

Findings

Small 3D-1D differences for neutral atoms and molecules.

Potential 0.3-0.4 dex differences for ions.

Differences increase with excitation potential and vary with wavelength.

Abstract

We compare the abundances of various chemical species as derived with 3D hydrodynamical and classical 1D stellar atmosphere codes in a late-type giant characterized by T_eff=3640K, log g = 1.0, [M/H] = 0.0. For this particular set of atmospheric parameters the 3D-1D abundance differences are generally small for neutral atoms and molecules but they may reach up to 0.3-0.4 dex in case of ions. The 3D-1D differences generally become increasingly more negative at higher excitation potentials and are typically largest in the optical wavelength range. Their sign can be both positive and negative, and depends on the excitation potential and wavelength of a given spectral line. While our results obtained with this particular late-type giant model suggest that 1D stellar atmosphere models may be safe to use with neutral atoms and molecules, care should be taken if they are exploited with ions.