Barium and europium abundances from the Gaia-ESO Survey using The Cannon

Neutron-capture element abundances encode the time-dependent interplay between slow (s-) and rapid (r-) nucleosynthetic processes and provide critical constraints on Galactic chemical evolution. In particular, barium and europium provide important tracers of s-process and r-process nucleosynthetic enrichment, respectively. Large spectroscopic surveys enable robust statistical studies of these elements; however, determining reliable elemental abundances at intermediate spectral resolution remains challenging. Our aim was to derive homogeneous and statistically well-characterised stellar parameters and chemical abundances of Ba and Eu (hereafter collectively referred to as stellar labels) for the -ESO Survey HR15N dataset. Gaia We applied to 36,263 FLAMES/GIRAFFE HR15N spectra (R ≈ 19 The Cannon , 200, łambda ∼ 6440-6815 Å), using a model trained on 782 stars with high-quality reference stellar labels drawn from the -ESO DR5 homogenised catalogue. The model infers T_̊m eff, łog g, $ Gaia Fe/H $, v i, A( ), and A( ); its reliability was quantified through multi-dimensional quality flags for the labels and detection strength of the Ba and Eu features. The uncertainties in the inferred stellar labels were obtained by combining the model's internal label-covariance errors with signal-to-noise-dependent dispersions. Ba Eu Our final catalogue contains stellar parameters for 36,263 spectra, with ∼21,000 and ∼400 reliable Ba and Eu abundances, respectively, satisfying multiple flagging criteria. We obtained median uncertainties of ∼38 K in T_̊m eff, ∼0.08 dex in łog g, ∼0.04 dex in $ Fe/H $, ∼0.06 dex in A( ), and ∼0.02 dex in A( ). External validation against the Benchmark Stars, GALAH DR4, and multiple open clusters shows good agreement across independent reference datasets. Ba Eu Gaia This study provides a comprehensive dataset of neutron-capture abundances in the Galactic disc observed with the -ESO HR15N set-up. The resulting catalogue includes newly determined Ba and Eu abundances that complement those available from previous analyses, thereby enabling well-characterised investigations of neutron-capture enrichment patterns in open clusters. The model framework can readily be adapted to upcoming wide-field spectroscopic surveys such as 4MOST, WEAVE, and WST. Gaia