Zeta-Payne: a fully automated spectrum analysis algorithm for the Milky Way Mapper program of the SDSS-V survey

Abstract

The Sloan Digital Sky Survey has recently initiated its 5th survey generation (SDSS-V), with a central focus on stellar spectroscopy. In particular, SDSS-V Milky Way Mapper program will deliver multi-epoch optical and near-infrared spectra for more than 5 million stars across the entire sky, covering a large range in stellar mass, surface temperature, evolutionary stage, and age. About 10% of those spectra will be of hot stars of OBAF spectral types, for whose analysis no established survey pipelines exist. Here we present the spectral analysis algorithm, Zeta-Payne, developed specifically to obtain stellar labels from SDSS-V spectra of stars with these spectral types and drawing on machine learning tools. We provide details of the algorithm training, its test on artificial spectra, and its validation on two control samples of real stars. Analysis with Zeta-Payne leads to only modest internal uncertainties in the near-IR with APOGEE (optical with BOSS): 3-10% (1-2%) for Teff, 5-30% (5-25%) for v*sin(i), 1.7-6.3 km/s(0.7-2.2 km/s) for RV, $<0.1$ dex ($<0.05$ dex) for log(g), and 0.4-0.5 dex (0.1 dex) for [M/H] of the star, respectively. We find a good agreement between atmospheric parameters of OBAF-type stars when inferred from their high- and low-resolution optical spectra. For most stellar labels the APOGEE spectra are (far) less informative than the BOSS spectra of these stars, while log(g), v*sin(i), and [M/H] are in most cases too uncertain for meaningful astrophysical interpretation. This makes BOSS low-resolution optical spectra better for stellar labels of OBAF-type stars, unless the latter are subject to high levels of extinction.

25 pages, 12 figures

References in corpus (17)

• The Gaia mission
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• Binary interaction dominates the evolution of massive stars
• The K2 Mission: Characterization and Early results
• The GALAH Survey: Scientific Motivation
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
• Low-frequency gravity waves in blue supergiants revealed by high-precision space photometry
• Signatures of internal rotation discovered in the Kepler data of five slowly pulsating B stars
• The Tarantula Massive Binary Monitoring: I. Observational campaign and OB-type spectroscopic binaries
• Hydrogen and helium line formation in OB dwarfs and giants. A hybrid non-LTE approach
• Photometric detection of internal gravity waves in upper main-sequence stars. II. Combined TESS photometry and high-resolution spectroscopy
• Three-Dimensional Simulations of Massive Stars: I. Wave Generation and Propagation
• The Physical Properties and Effective Temperature Scale of O-type Stars as a Function of Metallicity. III. More Results from the Magellanic Clouds
• The dependence of convective core overshooting on stellar mass: reality check, and additional evidence
• New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars. I. Method and first results
• Fully compressible simulations of waves and core convection in main-sequence stars
• The homogeneous characterisation of Ariel host stars