The cerium content of the Milky Way as revealed by Gaia DR3 GSP-Spec abundances

¹ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Bd de l’Observatoire, CS 34229, 06304 Nice cedex 4, France
e-mail: gabriele.contursi@oca.eu
² Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
³ INAF, Osservatorio di Astrofisica e Scienza dello Spazio, Via Gobetti 93/3, 40129 Bologna, Italy
⁴ Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy
⁵ INAF Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy
⁶ INFN Sezione di Trieste, via Valerio 2, 34134 Trieste, Italy
⁷ INAF – Osservatorio astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy
⁸ CIGUS CITIC – Department of Computer Science and Information Technologies, University of A Coruña, Campus de Elviña s/n, A Coruña 15071, Spain
⁹ Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, PR China

Received: 11 July 2022
Accepted: 16 November 2022

Abstract

Context. The recent Gaia third data release contains a homogeneous analysis of millions of high-quality Radial Velocity Spectrometer (RVS) stellar spectra by the GSP-Spec module. This led to the estimation of millions of individual chemical abundances and allows us to chemically map the Milky Way. The published GSP-Spec abundances include three heavy elements produced by neutron-captures in stellar interiors: Ce, Zr, and Nd.

Aims. We study the Galactic content in cerium based on these Gaia/RVS data and discuss the chemical evolution of this element.

Methods. We used a sample of about 30 000 local thermal equilibrium Ce abundances, selected after applying different combinations of GSP-Spec flags. Based on the Gaia DR3 astrometric data and radial velocities, we explore the cerium content in the Milky Way and, in particular, in its halo and disc components.

Results. The high quality of the Ce GSP-Spec abundances is quantified through literature comparisons. We found a rather flat [Ce/Fe] versus [M/H] trend. We also found a flat radial gradient in the disc derived from field stars and, independently, from about 50 open clusters. This agrees with previous studies. The [Ce/Fe] vertical gradient was also estimated. We also report an increasing [Ce/Ca] versus [Ca/H] in the disc, illustrating the late contribution of asymptotic giant branch stars with respect to supernovae of type II. Our cerium abundances in the disc, including the young massive population, are well reproduced by a new three-infall chemical evolution model. In the halo population, the M 4 globular cluster is found to be enriched in cerium. Moreover, 11 stars with cerium abundances belonging to the Thamnos, Helmi Stream, and Gaia-Sausage-Enceladus accreted systems were identified from chemo-dynamical diagnostics. We found that the Helmi Stream might be slightly underabundant in cerium compared to the two other systems.

Conclusions. This work illustrates the high quality of the GSP-Spec chemical abundances, which significantly contribute to unveiling the heavy-element evolution history of the Milky Way.