Neutron-Capture Element Signatures in Globular Clusters: Insights from the Gaia-ESO Survey

Abstract

Globular clusters (GCs) are key to understanding the formation and evolution of our Galaxy. While the abundances of light and Fe-peak elements in GCs have been widely studied, investigations into heavier, neutron-capture elements -- and their connection to multiple stellar populations and GC origins -- remain limited. In this work, we analysed the chemical abundances of neutron-capture elements in GCs to trace the Galactic halo and to explore possible links to the MP phenomenon. Our goal is to better constrain the nature of the polluters responsible for intracluster enrichment and to distinguish the origin of GCs through the chemical signature of neutron-capture elements. We examined 14 GCs from the Gaia-ESO Survey, spanning a wide metallicity range, [Fe/H] from -0.40 to -2.32, using a homogeneous methodology. We focused on the abundances of Y, Zr, Ba, La, Ce, Nd, Pr, and Eu, derived from FLAMES-UVES spectra. These were compared with predictions from a stochastic Galactic chemical evolution model. With the exception of Zr, the model broadly reproduces the observed trends in neutron-capture elements. In some GCs, we found strong correlations between hot H-burning products (Na, Al) and s-process elements, pointing to a shared nucleosynthesis site, e.g., asymptotic giant branch stars of different masses and/or fast-rotating massive stars. We also detect a distinct difference in [Eu/Mg] ratio between in-situ ($⟨$[Eu/Mg]$⟩$ = 0.14 dex) and ex-situ ($⟨$[Eu/Mg]$⟨$ = 0.32 dex) GCs, highlighting their different enrichment histories. Finally, on average, Type II GCs (NGC 362, NGC 1261, and NGC 1851) showed a s-process element spread ratio between second- and first-generations about twice as large as those seen in Type I clusters.

17 pages (11 main body + 6 Apprendix), 15 figures. Article accepted for publication A&A

References in corpus (41)

• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• Gaia EDR3 view on Galactic globular clusters
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
• What is a globular cluster? An observational perspective
• Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars
• The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy
• An abundance analysis of bright giants in the globular cluster NGC 1851
• The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products
• The role of neutron star mergers in the chemical evolution of the Galactic halo
• An inhomogeneous model for the Galactic halo: a possible explanation for the spread observed in s- and r-process elements
• Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process
• The Gaia-ESO Survey: processing of the FLAMES-UVES spectra
• $R$-process enhancements of Gaia-Enceladus in GALAH DR3
• The Gaia-ESO Survey: Kinematics of seven Galactic globular clusters
• The primordial and evolutionary abundance variations in globular-cluster stars: a problem with two unknowns
• The Gaia-ESO Survey: calibration strategy
• The Gaia-ESO Survey: Membership probabilities for stars in 63 open and 7 globular clusters from 3D kinematics
• Origin of neutron capture elements with the Gaia-ESO survey: the evolution of s- and r-process elements across the Milky Way
• The Gaia-ESO Survey: homogenisation of stellar parameters and elemental abundances
• Cluster Ages to Reconstruct the Milky Way Assembly (CARMA) I. The final word on the origin of NGC6388 and NGC6441
• Constraints on stellar rotation from the evolution of Sr and Ba in the Galactic halo
• Spectroscopy and photometry of the least-massive Type-II globular clusters: NGC1261 AND NGC6934
• Lithium abundances in globular cluster giants: NGC 6218 (M12) and NGC 5904 (M5)
• Chemical Evolution of R-process Elements in Stars (CERES). I. Stellar parameters and chemical abundances from Na to Zr
• On the serendipitous discovery of a Li-rich giant in the globular cluster NGC 362
• MINCE I. Presentation of the project and of the first year sample
• r-process Abundance Patterns in the Globular Cluster M92
• Young giants of intermediate mass Evidence of rotation and mixing
• CAPOS: The bulge Cluster APOgee Survey III. Spectroscopic Tomography of Tonantzintla 2
• APOGEE-2S Discovery of Light- and Heavy-Element Abundance Correlations in the Bulge Globular Cluster NGC 6380
• NGC 1261: an $r$-process enhanced globular cluster from the Gaia-Enceladus event
• Peeking beneath the precision floor I: metallicity spreads and multiple elemental dispersions in the globular clusters NGC 288 and NGC 362
• The Gaia-ESO survey: placing constraints on the origin of r-process elements
• Gaia-ESO Survey: Detailed elemental abundances in red giants of the peculiar globular cluster NGC 1851
• Modelling chemical clocks -- Theoretical evidences of the space and time evolution of [s/alpha] in the Galactic disc with Gaia-ESO survey
• Explaining the ${}^{12}\text{C}{/}^{13}\text{C}$ ratio in the Galactic halo: the contribution from shell mergers in primordial massive stars
• The in situ origin of the globular cluster NGC 6388 from abundances of Sc, V, and Zn of a large sample of stars
• Lithium abundances as a tracer of AGB stars pollution in the globular cluster NGC 6752
• The $Hubble$ Missing Globular Cluster Survey. I. Survey overview and the first precise age estimate for ESO452-11 and 2MASS-GC01
• MINCE III. Detailed chemical analysis of the UVES sample
• Neutron-capture elements in NGC 6752 multiple populations