Deep chemical tagging -- Identifying open clusters and moving groups in chemical space with graph attention networks

Abstract

Reconstructing the formation history of the Milky Way is hindered by stellar migration, which erases kinematic birth signatures. In contrast, stellar chemical abundances remain stable and can be used to trace stars back to their birth environments through chemical tagging. This study aims to improve chemical tagging by developing a method that leverages kinematic and age information to enhance clustering in chemical space, while remaining grounded in chemistry. We implement a graph attention auto-encoder that encodes stars as nodes with chemical features and connects them via edges based on orbital similarity and age. The network learns an ``informed'' chemical space that accentuates coherent groupings.Applied to $\sim$47,000 APOGEE thin disk stars, the method identifies 282 stellar groups. Among them, five out of six open clusters are successfully recovered. Other groups align with the known moving groups Arch/Hat, Sirius, Hyades, and Hercules. Our approach enables chemically grounded yet kinematically and age informed chemical tagging. It significantly improves the identification of coherent stellar populations, offering a framework for future large-scale stellar archaeology efforts.

12 pages, 8 figures, accepted for publication in A&A

References in corpus (32)

• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• galpy: A Python Library for Galactic Dynamics
• The New Galaxy: Signatures of its Formation
• Radial Mixing in Galactic Discs
• Chemical evolution with radial mixing
• Improving the open cluster census. II. An all-sky cluster catalogue with Gaia DR3
• Red giant masses and ages derived from carbon and nitrogen abundances
• Riding the kinematic waves in the Milky Way disk with Gaia
• Galactic Doppelganger: The chemical similarity among field stars and among stars with a common birth origin
• In the Galactic disk, stellar [Fe/H] and age predict orbits and precise [X/Fe]
• The 4:1 Outer Lindblad Resonance of a long slow bar as a potential explanation for the Hercules stream
• Testing the chemical tagging technique with open clusters
• Chemical tagging can work: Identification of stellar phase-space structures purely by chemical-abundance similarity
• Spectroscopic age estimates for APOGEE red-giant stars: Precise spatial and kinematic trends with age in the Galactic disc
• Prospects for chemically tagging stars in the Galaxy
• The Gaia-ESO survey: Calibrating a relationship between Age and the [C/N] abundance ratio with open clusters
• Chemical evidence for planetary ingestion in a quarter of Sun-like stars
• Unveiling the time evolution of chemical abundances across the Milky Way disk with APOGEE
• How Many Elements Matter?
• The GALAH survey: Chemical Tagging of Star Clusters and New Members in the Pleiades
• Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree
• Quantifying Chemical Tagging: Towards Robust Group Finding in the Galaxy
• Strong chemical tagging with APOGEE: 21 candidate star clusters that have dissolved across the Milky Way disc
• The (im)possibility of strong chemical tagging
• Tidally induced spiral arm wraps encoded in phase space
• Moving groups across Galactocentric radius with Gaia DR3
• From ridges to manifolds: 3D characterization of the moving groups in the Milky Way disc
• The Milky Way Bar Pattern Speed using Hercules and Gaia DR3
• Machine learning in APOGEE: Identification of stellar populations through chemical abundances
• The Gaia-ESO Survey: Chemical tagging in the thin disk. Open clusters blindly recovered in the elemental abundance space
• Radial and azimuthal gradients of the moving groups in Gaia DR3: The slow/fast bar degeneracy problem
• A baseline on the relation between chemical patterns and birth stellar cluster