High-resolution chemical makeup of the disrupted metal-poor stellar cluster ED-2

The ED-2 system is a recently identified kinematic substructure in the solar neighbourhood, characterized by its compactness in velocity space, indicating incomplete phase mixing. Photometric analysis suggests a single, old stellar population with an age of log(age/yr) = 10.20. In this work, we derived chemical abundances for 23 stars associated to ED-2 using high-resolution spectra acquired with the spectrographs UVES@VLT and PEPSI@LBT. We derived abundances of Fe, Mg, Na and Ca. The metallicity distribution function analysis, performed via a Markov Chain Monte Carlo approach, yields a mean [Fe/H] = -2.33 ± 0.01 dex for stars consistent with the best-fitting isochrone, with an intrinsic scatter consistent with a null spread. Abundances of Mg, Na, and Ca show no significant scatter, though key indicators for multiple populations (C, N, Al) remain unmeasured due to low signal-to-noise in the blue spectral range. The results support a scenario in which ED-2 represents the remnant of a metal-poor globular cluster accreted onto the Milky Way halo. Future observations targeting the blue spectral region will be crucial to confirm or rule out the presence of light-element anti-correlations, providing definitive insight into ED-2’s origin and contributing to the reconstruction of the early Galactic assembly.