The NewEra model grid

¹ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
² Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 USA
³ Planetary Science Institute, 1700 E. Fort Lowell Rd, Ste 106, Tucson, AZ 85719, USA
⁴ Homer L. Dodge Dept. of Physics and Astronomy, University of Oklahoma, 440 W. Brooks, Rm 100, Norman, OK 73019, USA
⁵ Department of Physical Sciences, College of Arts and Sciences, Embry-Riddle Aeronautical University, 1 Aerospace Boulevard, Daytona Beach, FL 32114, USA

^★ Corresponding author: yeti@hs.uni-hamburg.de

Received: 18 February 2025
Accepted: 23 April 2025

Abstract

Context. Analyses of stellar spectra, stellar populations, and transit light curves rely on grids of synthetic spectra and center-to-limb variations (limb darkening) from model stellar atmospheres. Extensive model grids from PHOENIX, a generalized non-local thermodynamic equilibrium (NLTE) 1D and 3D stellar atmosphere code, have found widespread use in the astronomical community, however current PHOENIX/1D models have been substantially improved over the last decade.

Aims. To make these improvements available to the community, we have constructed the NewEra LTE model grid consisting of 37438 models with 2300 K ≤ T_eff ≤ 12 000 K, 0.0 ≤ log (g) ≤ 6.0, metallicities [M/H] from −4.0 to +0.5, and for metallicities −2.0 ≤ [M/H] ≤ 0.0 additional α element variations from −0.2 ≤ [α/Fe] ≤ + 1.2 are included.

Methods. The models use databases of 851 million atomic lines and 834 billion molecular lines and employ the Astrophysical Chemical Equilibrium Solver for the equation of state. All models in the NewEra grid have been calculated in spherical symmetry because center-to-limb variation differences from plane-parallel models are quite large for giants and not insignificant for dwarfs.

Results. All model data are provided in the Hierarchical Data Format 5 (HDF5) format, including low and high sampling rate spectra. These files also include a variety of details about the models, such as the exact abundances and isotopic patterns used and results of the atomic and molecular line selection.

Conclusions. Although the model structures have small differences with the previous grid generation, the spectra show significant differences, mostly due to the updates of the molecular line lists.