GaiaData Release 3

Abstract

Context. The motion of stars has been used to reveal details of the complex history of the Milky Way, in constant interaction with its environment. Nevertheless, to reconstruct the Galactic history puzzle in its entirety, the chemo-physical characterisation of stars is essential. Previous Gaia data releases were supported by a smaller, heterogeneous, and spatially biased mixture of chemical data from ground-based observations. Aims. Gaia Data Release 3 opens a new era of all-sky spectral analysis of stellar populations thanks to the nearly 5.6 million stars observed by the Radial Velocity Spectrometer (RVS) and parametrised by the GSP-Spec module. In this work, we aim to demonstrate the scientific quality of Gaia's Milky Way chemical cartography through a chemo-dynamical analysis of disc and halo populations. Methods. Stellar atmospheric parameters and chemical abundances provided by Gaia DR3 spectroscopy are combined with DR3 radial velocities and EDR3 astrometry to analyse the relationships between chemistry and Milky Way structure, stellar kinematics, and orbital parameters.Results. The all-sky Gaia chemical cartography allows a powerful and precise chemo-dynamical view of the Milky Way with unprecedented spatial coverage and statistical robustness. First, it reveals the strong vertical symmetry of the Galaxy and the flared structure of the disc. Second, the observed kinematic disturbances of the disc -seen as phase space correlations-and kinematic or orbital substructures are associated with chemical patterns that favour stars with enhanced metallicities and lower [α/Fe] abundance ratios compared to the median values in the radial distributions. This is detected both for young objects that trace the spiral arms and older populations. Several α, iron-peak elements and at least one heavy element trace the thin and thick disc properties in the solar cylinder. Third, young disc stars show a recent chemical impoverishment in several elements. Fourth, the largest chemo-dynamical sample of open clusters analysed so far shows a steepening of the radial metallicity gradient with age, which is also observed in the young field population. Finally, the Gaia chemical data have the required coverage and precision to unveil galaxy accretion debris and heated disc stars on halo orbits through their [α/Fe] ratio, and to allow the study of the chemo-dynamical properties of globular clusters. Conclusions. Gaia DR3 chemo-dynamical diagnostics open new horizons before the era of ground-based wide-field spectroscopic surveys. They unveil a complex Milky Way that is the outcome of an eventful evolution, shaping it to the present day.

Imprints of Sagittarius accretion event: Young O-rich stars and discontinuous chemical evolution in Milky Way disc

“…A1. We obtain the luminosities of sample stars by cross-match them with the catalogue from Yu et al 2023 [15], which provides the luminosity of 1.5 million stars using astrometric data from GAIA DR3 [45] and improved interstellar extinction measurements. We utilised the orbital parameters (eccentricity) and velocities (U, V, W, and V Z ) from the GALAH DR3 value-added catalogue (VAC) [6].…”

The evolution of CNO elements in galaxies

“…The Galactic gradient Nowadays, samples of stars (both in the field and in OCs) from large surveys spanning wide ranges of distance and metallicity can be used to undisclose the full chemical enrichment histories of different Galactic components, revealing the details of the Milky Way assembly process over an unprecedented Galactic volume (e.g., Hayden et al 2015;Xiang et al 2019;Gaia Collaboration et al 2022;Randich et al 2022). Additional information on the dynamical processes that regulate the distribution of chemical species along the disc comes from the abundance gradients.…”

On the Evolutionary History of a Simulated Disk Galaxy as Seen by Phylogenetic Trees

“…Luckily, chemical abundances on an industrial scale are now available, which is revolutionizing the field of Galactic archeology, both due to direct discoveries from the data, as well as because they are necessary to validate chemical evolution models. In particular, thanks to surveys such as GALAH (Buder et al 2020), APOGEE (Majewski et al 2017;Abolfathi et al 2018;Holtzman et al 2018), and Gaia (Gaia Collaboration et al 2016a, 2016bBrown et al 2021;Eyer et al 2023;Recio-Blanco et al 2023), chemical abundances up to millions of stars are now available to better explore the processes that shaped the Galaxy.…”