VVV CL001: Likely the Most Metal-poor Surviving Globular Cluster in the Inner Galaxy - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Astrophysical journal letters Année : 2021

VVV CL001: Likely the Most Metal-poor Surviving Globular Cluster in the Inner Galaxy

Dante Minniti
Stefano Souza
Timothy Beers
Doug Geisler
Christian Moni Bidin
  • Fonction : Auteur
Sandro Villanova
Steven Majewski
Beatriz Barbuy
Angeles Pérez-Villegas
Lady Henao
María Romero-Colmenares
Alexandre Roman-Lopes
Richard Lane
  • Fonction : Auteur

Résumé

Abstract We present the first high-resolution abundance analysis of the globular cluster VVV CL001, which resides in a region dominated by high interstellar reddening toward the Galactic bulge. Using H -band spectra acquired by the Apache Point Observatory Galactic Evolution Experiment, we identified two potential members of the cluster, and estimated from their Fe i lines that the cluster has an average metallicity of [Fe/H] = −2.45 with an uncertainty due to systematics of 0.24 dex. We find that the light-(N), α -(O, Mg, Si), and Odd- Z (Al) elemental abundances of the stars in VVV CL001 follow the same trend as other Galactic metal-poor globular clusters. This makes VVV CL001 possibly the most metal-poor globular cluster identified so far within the Sun’s galactocentric distance and likely one of the most metal-deficient clusters in the Galaxy after ESO280-SC06. Applying statistical isochrone fitting, we derive self-consistent age, distance, and reddening values, yielding an estimated age of 11.9 − 4.05 + 3.12 Gyr at a distance of 8.22 − 1.93 + 1.84 kpc, revealing that VVV CL001 is also an old GC in the inner Galaxy. The Galactic orbit of VVV CL001 indicates that this cluster lies on a halo-like orbit that appears to be highly eccentric. Both chemistry and dynamics support the hypothesis that VVV CL001 could be an ancient fossil relic left behind by a massive merger event during the early evolution of the Galaxy, likely associated with either the Sequoia or the Gaia–Enceladus–Sausage structures.

Dates et versions

hal-03566853 , version 1 (11-02-2022)

Identifiants

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José Fernández-Trincado, Dante Minniti, Stefano Souza, Timothy Beers, Doug Geisler, et al.. VVV CL001: Likely the Most Metal-poor Surviving Globular Cluster in the Inner Galaxy. The Astrophysical journal letters, 2021, 908 (2), pp.L42. ⟨10.3847/2041-8213/abdf47⟩. ⟨hal-03566853⟩
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