CAPOS: The bulge Cluster APOgee Survey III. Spectroscopic Tomography of Tonantzintla 2

Abstract

We have performed the first detailed spectral analysis of red giant members of the relatively high-metallicity globular cluster (GC) Tononzintla 2 (Ton 2) using high-resolution near-infrared spectra collected with the Apache Point Observatory Galactic Evolution Experiment II survey (APOGEE-2), obtained as part of the bulge Cluster APOgee Survey. We investigate chemical abundances for a variety of species including the light-, odd-Z, α-, Fe-peak, and neutron-capture elements from high S/N spectra of seven giant members. The derived mean cluster metallicity is [Fe/H]= −0.70 ± 0.05, with no evidence for an intrinsic metallicity spread. Ton 2 exhibits a typical α-enrichment that follows the trend for high-metallicity Galactic GCs, similar to that seen in 47 Tucanae and NGC 6380. We find a significant nitrogen spread (> 0.87 dex), and a large fraction of nitrogen-enriched stars that populate the cluster. Given the relatively high-metallicity of Ton 2, these nitrogen-enriched stars are well above the typical Galactic levels, indicating the prevalence of the multiple-population phenomenon in this cluster which also contains several stars with typical low, first-generation N abundances. We also identify the presence of [Ce/Fe] abundance spread in Ton 2, which is correlated with the nitrogen enhancement, indicating that the s-process enrichment in this cluster has been produced likely by relatively low-mass Asymptotic Giant Branch stars. Furthermore, we find a mean radial velocity of the cluster, −178.6 ± 0.86 km s −1 with a small velocity dispersion, 2.99±0.61 km s −1 , which is typical of a GC. We also find a prograde bulge-like orbit for Ton 2 that appears to be radial and highly eccentric. Finally, the considerably nitrogen-enhanced population observed in Ton 2, combined with its dynamical properties, makes this object a potential progenitor for the nitrogen-enriched field stars identified so far toward the bulge region at similar metallicity.

APOGEE-2S view of the globular cluster Patchick 125 (Gran 3). New metallicity and elemental abundances from high-resolution spectroscopy

“…In addition, UKS 1, a heavily reddened GC, with E(B−V)∼2.62, was recently classified as a fossil relic of the bulge based on its chemodynamics properties (Fernández-Trincado et al 2020). These are examples of the wide gamut of highly reddened GCs examined so far towards the bulge area (see Saracino et al 2015;Schiavon et al 2017;Barbuy et al 2018a;Fernández-Trincado et al 2019Barbuy et al 2018bBarbuy et al , 2021Kunder & Butler 2020;Kunder et al 2021;Geisler et al 2021;Fernández-Trincado et al 2021e;Alonso-García et al 2021, for other cases).…”