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

TL;DR

This paper introduces a comprehensive database of 80,000 stellar atmosphere models for massive stars, enabling rapid spectral analysis across multiple wavelengths and demonstrating its application through reanalysis of a specific star.

Contribution

The creation of an extensive, multi-dimensional grid of stellar atmosphere models with synthetic spectra for efficient analysis of OB and Wolf-Rayet stars.

Findings

Reproduced previous stellar parameter estimates with improved mass-loss and clumping insights.

Demonstrated the utility of the model grid in reanalyzing stellar spectra.

Indicated UV resonance lines are influenced by velocity-space porosity.

Abstract

$Aims.$ We present a database of 43,340 atmospheric models ($\sim$80,000 models at the conclusion of the project) for stars with stellar masses between 9 and 120 $M_{\odot}$, covering the region of the OB main-sequence and Wolf-Rayet (W-R) stars in the Hertzsprung--Russell (H--R) 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 $T_{eff}$, the luminosity $L$, the metallicity $Z$, and three stellar wind parameters: the exponent $\beta$, the terminal velocity $V_{\infty}$, and the volume filling factor $F_{cl}$. For each model, we also calculate synthetic spectra in the UV (900-2000 A), optical (3500-7000 A), and near-IR (10000-40000 A) regions. To facilitate comparison with observations, the synthetic spectra can be rotationally broadened using ROTIN3, by covering vsin(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 $\epsilon$ 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.