Influence of departures from LTE on calcium, titanium, and iron abundance determinations in cool giants of different metallicities

TL;DR

This study investigates how non-LTE effects influence calcium, titanium, and iron abundance measurements in cool giant stars across various metallicities, providing correction data and an online tool.

Contribution

It offers detailed non-LTE abundance corrections for multiple spectral lines and introduces an online interpolation code for personalized corrections.

Findings

Non-LTE effects significantly affect abundance determinations.

Provided correction tables for 28-262 spectral lines.

Developed an online tool for non-LTE correction calculations.

Abstract

Non-local thermodynamic equilibrium (non-LTE) line formation for Ca I-Ca II, Ti I-Ti II, and Fe I-Fe II is considered in model atmospheres of giant stars with an effective temperature of 4000 K $\le$ Teff $\le$ 5000 K and a metal abundance of -4 $\le$ [Fe/H] $\le$ 0. The departures from LTE are analyzed depending on atmospheric parameters. We present the non-LTE abundance corrections for 28 lines of Ca I, 42 lines of Ti I, 54 lines of Ti II, and 262 lines of Fe I and a three-dimensional interpolation code to obtain the non-LTE correction online (http://spectrum.inasan.ru/nLTE/) for an individual spectral line and given atmospheric parameters.