The SAPP pipeline for the determination of stellar abundances and atmospheric parameters of stars in the core program of the PLATO mission

¹ Max Planck Institute for Astronomy, 69117 Heidelberg, Germany
e-mail: gent@mpia-hd.mpg.de
² Niels Bohr International Academy, NBI, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen, Denmark
³ Institute of Space Sciences (ICE, CSIC), Carrer de Can Magrans s/n, 08193 Cerdanyola del Valles, Spain
⁴ Institut d’Estudis Espacials de Catalunya (IEEC), Carrer Gran Capita 2, 08034 Barcelona, Spain
⁵ Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Quartier Agora, Allée du 6 Août 19c, Bât. B5C, 4000 Liège, Belgium
⁶ Observational Astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
⁷ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Lagrange, CS 34229, Nice, France
⁸ Research School of Astronomy & Astrophysics, Mount Stromlo Observatory, Australian National University, ACT 2611, Australia
⁹ Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, CP 226, Boulevard du Triomphe, 1050 Brussels, Belgium
¹⁰ ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, Szent Imre H. St. 112, 9700 Szombathely, Hungary
¹¹ MTA-ELTE Exoplanet Research Group, Hungary
¹² MTA-ELTE Lendület Milky Way Research Group, Hungary
¹³ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
¹⁴ Observatoire Paris-Site de Meudon, LESIA, 5 Pl Jules Janssen, 92195 Meudon Cedex, France
¹⁵ Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, Sta. Ma. Tonantzintla, Puebla CP 72840, Mexico
¹⁶ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
¹⁷ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
¹⁸ Istituto Nazionale di Astrofisica – INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
¹⁹ Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
²⁰ Université de Toulouse, UPS-OMP, IRAP, 31028 Toulouse Cedex 4, France
²¹ CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
²² LUPM, Univ. Montpellier, CNRS, Montpellier, France
²³ Yunnan Observatories, Chinese Academy of Sciences, PO Box 110 Kunming 650216, PR China
²⁴ Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120/1520, 8000 Aarhus, Denmark
²⁵ Space Science Institute, 4765 Walnut Street, Boulder, CO 80301, USA
²⁶ LESIA, Observatoire de Paris, Bât. 14 – Soleil-Planètes, 5 Place Jules Janssen, 92195 Meudon, France

Received: 23 March 2021
Accepted: 8 November 2021

Abstract

We introduce the SAPP (Stellar Abundances and atmospheric Parameters Pipeline), the prototype of the code that will be used to determine parameters of stars observed within the core program of the PLATO space mission. The pipeline is based on the Bayesian inference and provides effective temperature, surface gravity, metallicity, chemical abundances, and luminosity. The code in its more general version has a much wider range of potential applications. It can also provide masses, ages, and radii of stars and can be used with stellar types not targeted by the PLATO core program, such as red giants. We validate the code on a set of 27 benchmark stars that includes 19 FGK-type dwarfs, 6 GK-type subgiants, and 2 red giants. Our results suggest that combining various observables is the optimal approach, as this allows the degeneracies between different parameters to be broken and yields more accurate values of stellar parameters and more realistic uncertainties. For the PLATO core sample, we obtain a typical uncertainty of 27 (syst.) ± 37 (stat.) K for T_eff, 0.00 ± 0.01 dex for log g, 0.02 ± 0.02 dex for metallicity [Fe/H], −0.01 ± 0.03 R_⊙ for radii, −0.01 ± 0.05 M_⊙ for stellar masses, and −0.14 ± 0.63 Gyr for ages. We also show that the best results are obtained by combining the ν_max scaling relation with stellar spectra. This resolves the notorious problem of degeneracies, which is particularly important for F-type stars.