SDSS-IV MaStar: [α/Fe] for the MaNGA Stellar Library from synthetic model spectra

ABSTRACT We calculate the α-enhancement ratio [α/Fe] for Mapping Nearby Galaxies at APO (MaNGA) Stellar Library (MaStar) while also fitting fundamental atmospheric parameters effective temperature, surface gravity, and metallicity – Teff, log g, [Fe/H]. This approach builds upon a previous catalogue of stellar parameters, whereby only are fit with solar-scaled models. Here, we use same Markov Chain Monte Carlo method additional free parameter [α/Fe]. Using full spectral code pPXF, able to multiple lines sensitive more robust measurement. Quality flags based on convergence sampler, errors in cut χ2 model used clean final catalogue, returning 17 214 spectra values range −0.25 < 0.48. Comparing our calculated literature reveals degeneracy cool stars g ≥ ∼4; this comparison is then create an alternative calibrated set. plot [Fe/H] versus diagram recover expected result increasing decreasing Milky Way disc-halo stars. apply subsample uniform resolution higher signal noise that finds results independent noise. In context population models, cover space creation intermediate old age models [α/Fe], high enhanced low