Abundance Analysis of the Halo Giant HD122563 with Three-Dimensional Model Stellar Atmospheres

TL;DR

This study compares 3D hydrodynamical and traditional 1D models to analyze the elemental abundances in the metal-poor halo giant HD122563, revealing significant differences due to model dimensionality and temperature stratification.

Contribution

It introduces a 3D LTE abundance analysis for a metal-poor star and compares it with 1D results, highlighting the impact of model dimensionality on abundance determinations.

Findings

Large negative 3D-1D abundance differences for low-excitation lines.

Presence of trends with excitation potential in Fe I line abundances.

Differences attributed to temperature stratification and LTE assumptions.

Abstract

We present a preliminary local thermodynamic equilibrium (LTE) abundance analysis of the template halo red giant HD122563 based on a realistic, three-dimensional (3D), time-dependent, hydrodynamical model atmosphere of the very metal-poor star. We compare the results of the 3D analysis with the abundances derived by means of a standard LTE analysis based on a classical, 1D, hydrostatic model atmosphere of the star. Due to the different upper photospheric temperature stratifications predicted by 1D and 3D models, we find large, negative, 3D-1D LTE abundance differences for low-excitation OH and Fe I lines. We also find trends with lower excitation potential in the derived Fe LTE abundances from Fe I lines, in both the 1D and 3D analyses. Such trends may be attributed to the neglected departures from LTE in the spectral line formation calculations.