Gaia Data Release 3

Analysis of the Gaia BP/RP spectra using the General Stellar Parameterizer from Photometry

¹ Max Planck Institute for Astronomy, Knigstuhl 17, 69117 Heidelberg, Germany
Corresponding author: R. Andrae, e-mail: andrae@mpia-hd.mpg.de
² INAF – Osservatorio astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy
³ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁴ INAF – Osservatorio Astrofisico di Torino, via Osservatorio 20, 10025 Pino Torinese (TO), Italy
⁵ Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
⁶ DXC Technology, Retortvej 8, 2500 Valby, Denmark
⁷ IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
⁸ Observational Astrophysics, Division of Astronomy and Space Physics, Department of Physics and Astronomy, Uppsala University, Box 516 751 20 Uppsala, Sweden
⁹ Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
¹⁰ GEPI, Observatoire de Paris, Université PSL, CNRS, 5 Place Jules Janssen, 92190 Meudon, France
¹¹ ATG Europe for European Space Agency (ESA), Camino bajo del Castillo, s/n, Urbanizacion Villafranca del Castillo, Villanueva de la Cañada, 28692 Madrid, Spain
¹² CIGUS CITIC – Department of Computer Science and Information Technologies, University of A Coruña, Campus de Elviña s/n, A Coruña, 15071, Spain
¹³ National Observatory of Athens, I. Metaxa and Vas. Pavlou, Palaia Penteli, 15236 Athens, Greece
¹⁴ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Bd de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
¹⁵ INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
¹⁶ Telespazio for CNES Centre Spatial de Toulouse, 18 avenue Édouard Belin, 31401 Toulouse Cedex 9, France
¹⁷ Dpto. de Matemática Aplicada y Ciencias de la Computación, Univ. de Cantabria, ETS Ingenieros de Caminos, Canales y Puertos, Avda. de los Castros s/n, 39005 Santander, Spain
¹⁸ CNES Centre Spatial de Toulouse, 18 avenue Édouard Belin, 31401 Toulouse Cedex 9, France
¹⁹ Centre for Astrophysics Research, University of Hertfordshire, College Lane, AL10 9AB Hatfield, UK
²⁰ Institut d’Astrophysique et de Géophysique, Université de Liège, 19c, Allée du Six-Août, 4000 Liège, Belgium
²¹ APAVE SUDEUROPE SAS for CNES Centre Spatial de Toulouse, 18 avenue Édouard Belin, 31401 Toulouse Cedex 9, France
²² Theoretical Astrophysics, Division of Astronomy and Space Physics, Department of Physics and Astronomy, Uppsala University, Box 516 751 20 Uppsala, Sweden
²³ Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium
²⁴ European Space Agency (ESA), European Space Astronomy Centre (ESAC), Camino bajo del Castillo, s/n, Urbanizacion Villafranca del Castillo, Villanueva de la Cañada, 28692 Madrid, Spain
²⁵ Data Science and Big Data Lab, Pablo de Olavide University, 41013 Seville, Spain
²⁶ Department of Astrophysics, Astronomy and Mechanics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, 15783 Athens, Greece
²⁷ Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, Via S. Sofia 64, 95123 Catania, Italy
²⁸ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 Place Jules Janssen, 92190 Meudon, France
²⁹ Université Rennes, CNRS, IPR (Institut de Physique de Rennes) – UMR 6251, 35000 Rennes, France
³⁰ Aurora Technology for European Space Agency (ESA), Camino bajo del Castillo, s/n, Urbanizacion Villafranca del Castillo, Villanueva de la Cañada, 28692 Madrid, Spain
³¹ CIGUS CITIC, Department of Nautical Sciences and Marine Engineering, University of A Coruña, Paseo de Ronda 51, 15071 A Coruña, Spain
³² IPAC, Mail Code 100-22, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA
³³ Thales Services for CNES Centre Spatial de Toulouse, 18 avenue Édouard Belin, 31401 Toulouse Cedex 9, France
³⁴ Dpto. de Inteligencia Artificial, UNED, c/ Juan del Rosal 16, 28040 Madrid, Spain
³⁵ Institute of Global Health, University of Geneva, Geneva, Switzerland
³⁶ Applied Physics Department, Universidade de Vigo, 36310 Vigo, Spain
³⁷ Sorbonne Université, CNRS, UMR7095, Institut d’Astrophysique de Paris, 98bis bd. Arago, 75014 Paris, France

Received: 3 March 2022
Accepted: 4 May 2022

Abstract

Context. The astrophysical characterisation of sources is among the major new data products in the third Gaia Data Release (DR3). In particular, there are stellar parameters for 471 million sources estimated from low-resolution BP/RP spectra.

Aims. We present the General Stellar Parameterizer from Photometry (GSP-Phot), which is part of the astrophysical parameters inference system (Apsis). GSP-Phot is designed to produce a homogeneous catalogue of parameters for hundreds of millions of single non-variable stars based on their astrometry, photometry, and low-resolution BP/RP spectra. These parameters are effective temperature, surface gravity, metallicity, absolute M_G magnitude, radius, distance, and extinction for each star.

Methods. GSP-Phot uses a Bayesian forward-modelling approach to simultaneously fit the BP/RP spectrum, parallax, and apparent G magnitude. A major design feature of GSP-Phot is the use of the apparent flux levels of BP/RP spectra to derive, in combination with isochrone models, tight observational constraints on radii and distances. We carefully validate the uncertainty estimates by exploiting repeat Gaia observations of the same source.

Results. The data release includes GSP-Phot results for 471 million sources with G <  19. Typical differences to literature values are 110 K for T_eff and 0.2–0.25 for log g, but these depend strongly on data quality. In particular, GSP-Phot results are significantly better for stars with good parallax measurements (ϖ/σ_ϖ >  20), mostly within 2 kpc. Metallicity estimates exhibit substantial biases compared to literature values and are only useful at a qualitative level. However, we provide an empirical calibration of our metallicity estimates that largely removes these biases. Extinctions A₀ and A_BP show typical differences from reference values of 0.07–0.09 mag. MCMC samples of the parameters are also available for 95% of the sources.

Conclusions. GSP-Phot provides a homogeneous catalogue of stellar parameters, distances, and extinctions that can be used for various purposes, such as sample selections (OB stars, red giants, solar analogues etc.). In the context of asteroseismology or ground-based interferometry, where targets are usually bright and have good parallax measurements, GSP-Phot results should be particularly useful for combined analysis or target selection.