J/A+A/648/A108 Heavy-elements heritage of the falling sky (Recio-Blanco+, 2021) ================================================================================ Heavy-elements heritage of the falling sky. Recio-Blanco A., Fernandez-Alvar E., de Laverny P., Antoja T., Helmi A., Crida A. =2021A&A...648A.108R (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Milky Way ; Clusters, globular ; Stars, nearby ; Abundances Keywords: Galaxy: abundances - Galaxy: halo - Galaxy: stellar content - Galaxy: formation Abstract: A fundamental element of galaxy formation is the accretion of mass through mergers of satellites or gas. Recent dynamical analyses based on Gaia data have revealed major accretion events in the history of the Milky Way. Nevertheless, our understanding of the primordial Galaxy is hindered because the bona fide identification of the most metal-poor and correspondingly oldest accreted stars remains challenging. Galactic archaeology needs a new accretion diagnostic to understand primordial stellar populations. Contrary to {alpha}-elements, neutron-capture elements present unexplained large abundance spreads for low-metallicity stars, which could result from a mixture of formation sites. We analysed the abundances of yttrium, europium, magnesium, and iron in MilkyWay satellite galaxies, field halo stars, and globular clusters. The chemical information was complemented by orbital parameters based on Gaia data. In particular, we considered the average inclination of the orbits. The [Y/Eu] abundance behaviour with respect to the [Mg/Fe] turnovers for satellite galaxies of various masses reveals that higher-luminosity systems, for which the [Mg/Fe] abundance declines at higher metallicities, present enhanced [Y/Eu] abundances, particularly in the [Fe/H] regime between -2.25dex and -1.25dex. In addition, the analysis has uncovered a chemo-dynamical correlation for both globular clusters and field stars of the Galactic halo, accounting for about half of the [Y/Eu] abundance spread. In particular, [Y/Eu] under-abundances typical of protracted chemical evolutions are preferentially observed in polar-like orbits, pointing to a possible anisotropy in the accretion processes. Our results strongly suggest that the observed [Y/Eu] abundance spread in the Milky Way halo could result from a mixture of systems with different masses. They also highlight that both nature and nurture are relevant to the formation of the Milky Way since its primordial epochs, thereby opening new pathways for chemical diagnostics of the build-up of our Galaxy. Description: Sample of chemical abundances and orbital parameters used in the paper. It comprises several samples of objects: globular clusters and field stars, from the Milky Way. We made use of abundances of europium, yttrium, and [Mg/Fe], collected from multiple literature works (see Column 1 of this Table 2, but also Table 1 of the paper, not in electronic form). Field stars abundances come from two different compilations: a photometric selection of metal-poor stars (Roederer et al., 2014AJ....147..136R, Cat. J/AJ/147/136) and a study of heavy-element abundances for high-alpha and low-alpha stars at intermediate metallicity (Fishlock et al., 2017MNRAS.466.4672F). Globular cluster abundances come for a compilation of literature works used in Recio-Blanco (2018A&A...620A.194R). For a description of the orbital inclination estimates see Section 3 in the paper. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 54 61 Chemical abundances and orbital parameters -------------------------------------------------------------------------------- See also: J/AJ/147/136 : Stars of very low metal abundance. VI. Abundances (Roederer+, 2014) J/MNRAS/484/2832 : Proper motions of Milky Way globular clusters (Vasiliev, 2019) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 12 A12 --- Ref References code (1) 14- 25 A12 --- Object Target name 27- 31 F5.2 [-] [Fe/H] Iron abundance 33- 36 F4.2 [-] [alpha/Fe] ?=9.99 alpha element abundance with respect to iron 38- 42 F5.2 [-] [Y/Fe] Yttrium abundance with respect to iron 44- 48 F5.2 [-] [Eu/Fe] Europium abundance with respect to iron 50- 54 F5.1 deg Incl Orbital inclination -------------------------------------------------------------------------------- Note (1): References code as follows: F2017 = Fishlock et al., 2017MNRAS.466.4672F R2018 = Recio-Blanco, 2018A&A...620A.194R R2014 = Roederer et al., 2014AJ....147..136R, Cat. J/AJ/147/136 V2018 = Vasiliev, 2019MNRAS.484.2832V, Cat, J/MNRAS/484/2832 -------------------------------------------------------------------------------- Acknowledgements: Alejandra Recio-Blanco, alejandra.recio-blanco(at)oca.eu ================================================================================ (End) A. Recio-Blanco [Observatoire Cote d'Azur], P. Vannier [CDS] 19-Apr-2021