SDSS-IV MaStar: theoretical atmospheric parameters for the MaNGA stellar library

We calculate the fundamental stellar parameters effective temperature, surface gravity and abundance - Teff, log g, [Fe/H] - for the final release of the Mapping Nearby Galaxies APO (MaNGA) Stellar Library (MaStar), containing 59,266 per-visit-spectra for 24,290 stars at intermediate resolution (푅 ∼ 1800) and high S/N (median = 96). We fit theoretical spectra from model atmospheres by both MARCS and BOSZ-ATLAS9 to the observed spectra, using the full spectral fitting code pPXF. We further employ a Bayesian approach, using a Markov Chain Monte Carlo (MCMC) technique to map the parameter space obtain uncertainties. Originally in this paper, we cross match MaStar observations with photometry, which enable us to set reliable priors and identify outliers according to evolution. In parallel to the parameter determination, we calculate corresponding stellar models to test the reliability of the parameters for each stellar evolutionary phase. further assess our procedure by determining parameters for standard stars such as the and Vega and by comparing our parameters with those determined in the literature from-resolution spectroscopy (APOGEE and SEGUE) and from lower-resolution matching (LAMOST). The comparisons, considering the different methodologies and S/N of literature surveys, are favourable in all cases. Our final parameter catalogue for MaStar the following ranges: 2592 6 Teff 6 32983 K; −0.7 6 log g 6 5.4 dex; −2.9 6 [Fe/H]6 1.0 dex and will be available with the last SDSS-IV Data Release, in December 2021.