Creating and using large grids of precalculated model atmospheres for a rapid analysis of stellar spectra

Abstract

Aims. We present a database of 43 340 atmospheric models (∼80 000 models at the conclusion of the project) for stars with stellar masses between 9 and 120 M⊙, covering the region of the OB main-sequence and Wolf-Rayet stars in the Hertzsprung-Russell diagram. Methods. The models were calculated using the ABACUS I supercomputer and the stellar atmosphere code CMFGEN. Results. The parameter space has six dimensions: the effective temperature Teff, the luminosity L, the metallicity Z, and three stellar wind parameters: the exponent β, the terminal velocity V∞, and the volume filling factor Fcl. For each model, we also calculate synthetic spectra in the UV (900−2000 Å), optical (3500−7000 Å), and near-IR (10 000−40 000 Å) regions. To facilitate comparison with observations, the synthetic spectra can be rotationally broadened using ROTIN3, by covering v sin i velocities between 10 and 350 km s−1 with steps of 10 km s−1. Conclusions. We also present the results of the reanalysis of ϵ Ori using our grid to demonstrate the benefits of databases of precalculated models. Our analysis succeeded in reproducing the best-fit parameter ranges of the original study, although our results favor the higher end of the mass-loss range and a lower level of clumping. Our results indirectly suggest that the resonance lines in the UV range are strongly affected by the velocity-space porosity, as has been suggested by recent theoretical calculations and numerical simulations.

MSG: A software package for interpolating stellar spectra in pre-calculated grids

“…There are a wide variety of stellar spectral grids published in the astronomical literatureexamples include Lanz & Hubeny (2003), Lanz & Hubeny (2007), Kirby (2011), de Laverny et al (2012, Husser et al (2013), Allende Prieto et al (2018), Chiavassa et al (2018) and Zsargó et al (2020). However, the ecosystem of software packages that offer users the ability to interpolate in these grids is much more limited:…”

Photoionization and electron-ion recombination in astrophysical plasmas

“…A grid of spectra are available from the Pollux data base [124]. A large grid of CMFGEN spectra models has been constructed and is being made available [125,126]. Hillier will also provide CMFGEN models upon request.…”

Design of an Artificial Neural Network for the Analysis of Stellar Spectra

“…The Far Ultraviolet Spectroscopic Explorer (FUSE) 2 , the International Ultraviolet Explorer (IUE) 3 in ultraviolet (UV), the Hubble Space Telescope (HST) 4 in UV and optical, and the Sloan Digital Sky Survey (SDSS) 5 [1] in optical e IR, to mention a few, have generated databases of stellar spectra on the order of the petabytes. On the other hand, there are databases of synthetic stellar spectra with tens, hundreds and even thousands of stellar models, with their corresponding synthetic spectra in the optical, UV and IR (see, for example, the grids for Wolf-Rayet (WR) stars [2], the POLLUX database [3] and the grids of models for OB stars [4,5,6] calculated with the CMFGEN code [7]. Such databases of theoretical spectra have produced data volumes on the order of the terabytes.…”