Chemodynamical properties and ages of metal-poor stars in S-PLUS

Metal-poor stars are key to our understanding of the early stages of chemical evolution in the Universe. New multifilter surveys, such as the Southern Photometric Local Universe Survey (S-PLUS), are greatly advancing our ability to select low-metallicity stars. In this work, we analyse the chemodynamical properties and ages of 522 metal-poor candidates selected from the S-PLUS data release 3. About 92 per cent of these stars were confirmed to be metal-poor ([Fe/H] ≤ −1) based on previous medium-resolution spectroscopy. We calculated the dynamical properties of a subsample containing 241 stars, using the astrometry from Gaia Data Release 3. Stellar ages are estimated by a Bayesian isochronal method formalized in this work. We analyse the metallicity distribution of these metal-poor candidates separated into different subgroups of total velocity, dynamical properties, and ages. Our results are used to propose further restrictions to optimize the selection of metal-poor candidates in S-PLUS. The proposed astrometric selection (parallax >0.85 mas) is the one that returns the highest fraction of extremely metal-poor stars (16.3 per cent have [Fe/H] ≤ −3); the combined selection provides the highest fraction of very metal-poor stars (91.0 per cent have [Fe/H] ≤ −2), whereas the dynamical selection (eccentricity >0.35 and discness < 0.75) is better for targeting metal-poor (99.5 per cent have [Fe/H] ≤ −1). Using only S-PLUS photometric selections, it is possible to achieve selection fractions of 15.6, 88.5, and 98.3 per cent for metallicities below −3, −2, and −1, respectively. We also show that it is possible to use S-PLUS to target metal-poor stars in halo substructures such as Gaia-Sausage/Enceladus, Sequoia, Thamnos, and the Helmi stream.The work of V.M.P. is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. F.A.-F. acknowledges funding for this work from FAPESP grants 2018/20977-2 and 2021/09468-1. G.L. acknowledges FAPESP (procs. 2021/10429-0 and 2022/07301-5). L.B.S acknowledges the support of NASA-ATP award 80NSSC20K0509 and U.S. National Science Foundation AAG grant AST-2009122. J.A. acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 852839). H.D.P. thanks FAPESP (procs. 2018/21250-9 and 2022/04079-0). The S-PLUS project, including the T80-South robotic telescope and the S-PLUS scientific survey, was founded as a partnership between the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), the Observatório Nacional (ON), the Federal University of Sergipe (UFS), and the Federal University of Santa Catarina (UFSC), with important financial and practical contributions from other collaborating institutes in Brazil, Chile (Universidad de La Serena), and Spain (Centro de Estudios de Física del Cosmos de Aragón, CEFCA). We further acknowledge financial support from the São Paulo Research Foundation (FAPESP), Fundação de Amparo à Pesquisa do Estado do Rs (FAPERGS), the Brazilian National Research Council (CNPq), the Coordination for the Improvement of Higher Education Personnel (CAPES), the Carlos Chagas Filho Rio de Janeiro State Research Foundation (FAPERJ), and the Brazilian Innovation Agency (FINEP).Peer reviewe