SDSS-IV MaStar: Stellar parameter determination with continuum-supplemented full-spectrum fitting

Daniel Lazarz, Renbin Yan, Ronald Wilhelm, Yanping Chen, Lewis Hill, Jon A. Holtzman, Julie Imig, Claudia Maraston, Szabolcs Mészáros, Guy S. Stringfellow, Daniel Thomas, Timothy C. Beers, Dmitry Bizyaev, Niv Drory, Richard R. Lane, Christian Nitschelm

Research output: Contribution to journalArticlepeer-review


Aims. We present a stellar parameter catalog built to accompany the MaStar Stellar Library, which is a comprehensive collection of empirical, medium-resolution stellar spectra. Methods. We constructed this parameter catalog by using a multicomponent χ 2 fitting approach to match MaStar spectra to models generated by interpolating the ATLAS9-based BOSZ model spectra. The total χ 2 for a given model is defined as the sum of components constructed to characterize narrow-band features of observed spectra (e.g., absorption lines) and the broadband continuum shape separately. Extinction and systematics due to flux calibration were taken into account in the fitting. The χ 2 distribution for a given region of model space was sampled using a Markov chain Monte Carlo (MCMC) algorithm, the data from which were then used to extract atmospheric parameter estimates (Teff, log g, [Fe/H], and [α/Fe]), their corresponding uncertainties, and direct extinction measurements. Results. Two methods were used to extract parameters and uncertainties: one that accepts the MCMC' s prescribed minimum-χ 2 result, and one that uses Bayesian inference to compute a likelihood-weighted mean from the χ 2 distribution sampled by the MCMC. Results were evaluated for internal consistency using repeat observations where available and by comparing them with external data sets (e.g., APOGEE-2 and Gaia DR2). Our spectral-fitting exercise reveals possible deficiencies in current theoretical model spectra, illustrating the potential power of MaStar spectra for helping to improve the models. This paper represents an update to the parameters that were originally presented with SDSS-IV DR17. The MaStar parameter catalog containing our BestFit results is available on the SDSS-IV DR17 website as part of version 2 of the MaStar stellar parameter value-added catalog.

Original languageEnglish
Article numberA21
JournalAstronomy and Astrophysics
StatePublished - Dec 1 2022

Bibliographical note

Funding Information:
D.L., R.Y., and R.W. would like to acknowledge support by the NSF grant AST-1715898. R.Y. would like to acknowledge support by the Hong Kong Global STEM Scholar scheme, by the Hong Kong Jockey Club through the JC STEM Lab of Astronomical Instrumentation program, by the Direct Grant of CUHK Faculty of Science, and by the Research Grant Council of the Hong Kong Special Administrative Region, China (Projects No. 14302522). T.C.B. acknowledges partial support for this work from grant PHY 14-30152; Physics Frontier Center/JINA Center for the Evolution of the Elements (JINA-CEE), awarded by the US National Science Foundation. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the US Department of Energy Office of Science, and the Participating Institutions. S.D.S.S. acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is . SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, Center for Astrophysics | Harvard & Smithsonian (CfA), the Chilean Participation Group, the French Participation Group, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU) / University of Tokyo, the Korean Participation Group, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observatório Nacional / MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University.

Publisher Copyright:
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  • Hertzsprung- Russell and C- M diagrams
  • Methods: data analysis
  • Stars: abundances
  • Stars: atmospheres

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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