GALA cookbook

TL;DR

GALA is a Fortran-based tool that determines stellar atmospheric parameters and element abundances using spectral line equivalent widths, supporting multiple model atmosphere grids and providing graphical analysis tools.

Contribution

This paper introduces GALA, a versatile code that integrates various model atmospheres and enhances abundance analysis with graphical and statistical tools.

Findings

Supports multiple model atmosphere grids including ATLAS9 and MARCS.

Automates the derivation of stellar parameters and abundances.

Provides graphical tools for evaluating solution quality.

Abstract

GALA (Mucciarelli et al. 2013) is a code written in standard Fortran 77 and aimed at finding the best atmospheric parameters and the abundance of individual elements by using the equivalent widths (EWs) of metallic lines, providing graphical and statistical tools to evaluate the goodness of the solution. The derivation of the abundances is performed by using a modified version of the WIDTH9 code(originally developed by R. L. Kurucz) in its Linux version (Sbordone et al. 2004). In the current release, GALA can manage the classical grid of ATLAS9 models computed by (Castelli & Kurucz, 2004), the grid of new ATLAS9 models computed for the APOGEE survey (Mezsaros et al., 2012) and the MARCS models with the standard composition (Gustafsson et al., 2008). When the ATLAS9 models are used, new model atmospheres are calculated starting from an existing guess model and according to the pre-tabulated Opacity Distribution Functions (ODF) and Rosseland opacity tables. When MARCS are used, each new model is obtained by interpolating within the MARCS grid.