The KOALA database provides a grid of LTE, line-blanketed model atmospheres computed with the ATLAS9 code (Kurucz 1970; Kurucz et al. 1974; Kurucz 2005), along with the corresponding opacity distribution functions and emergent fluxes. These fluxes have been used to derive G-band bolometric corrections and theoretical colours across a wide range of photometric systems, including UBVRI, 2MASS, Hipparcos-Tycho, SDSS, Galex, Euclid, and Gaia DR3.
What sets KOALA apart from previous ATLAS9 grids?
It adopts the Caffau/Lodders solar abundance mixture.
It extends the parameter coverage in both metallicity (–5.0 to +0.5 dex, with finer steps at higher metallicities) and [α/Fe] ratios (–0.4 to +0.4 dex in Δ=0.2 dex increments).
For stars cooler than T< 7000 K, it provides finer sampling in effective temperature, improving the accuracy of colour interpolation and, in many cases, reducing the need for computing additional tailored models.
The database currently comprises a total of 51,663 model atmospheres and emergent fluxes, representing a significant expansion of ATLAS9-based resources for stellar astrophysics and photometric applications.