Interpolation of spectra from 3D model atmospheres

¹ Instituto de Astrofísica de Canarias, Vía Láctea, 38205 La Laguna, Tenerife, Spain
e-mail: callende@iac.es
² Universidad de La Laguna, Departamento de Astrofísica, 38206 La Laguna, Tenerife, Spain
³ Zentrum für Astronomie der Universität Heidelberg. Landessternwarte, Königstuhl 12, 69117 Heidelberg, Germany
⁴ Texas Advanced Computing Center, University of Texas, Austin, TX 78759, USA

Received: 19 January 2022
Accepted: 24 January 2022

Abstract

Context. The use of 3D hydrodynamical simulations of stellar surface convection for model atmospheres is computationally expensive. Although these models have been available for quite some time, their use is limited because of the lack of extensive grids of simulations and associated spectra.

Aims. Our goal is to provide a method to interpolate spectra that can be applied to both 1D and 3D models, and implement it in a code available to the community. This tool will enable the routine use of 3D model atmospheres in the analysis of stellar spectra.

Methods. We have developed a code that makes use of radial basis functions to interpolate the spectra included in the CIFIST grid of 84 three-dimensional model atmospheres. Spectral synthesis on the hydrodynamical simulations was previously performed with the code ASSϵT.

Results. We make a tool for the interpolation of 3D spectra available to the community. The code provides interpolated spectra and interpolation errors for a given wavelength interval, and a combination of effective temperature, surface gravity, and metallicity. In addition, it optionally provides graphical representations of the RMS and mean ratio between 1D and 3D spectra, and maps of the errors in the interpolated spectra across the parameter space.