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

Journal Article · 07 February 2022 · Astronomy and Astrophysics

DOI: https://doi.org/10.1051/0004-6361/202141742 · OSTI ID:1982298

Fernández-Trincado, José G. ^[1]; Villanova, Sandro ^[2]; Geisler, Doug ^[3]; Barbuy, Beatriz ^[4]; Minniti, Dante ^[5]; Beers, Timothy C. ^[6]; Mészáros, Szabolcs ^[7]; Tang, Baitian ^[8]; Cohen, Roger E. ^[9]; Moni Bidin, Cristian ^[1]; Garro, Elisa R. ^[10]; Baeza, Ian ^[2]; Muñoz, Cesar ^[11]

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1. Universidad Católica del Norte (Chile)
2. Universidad de Concepción (Chile)
3. Universidad de Concepción (Chile); Universidad de La Serena (Chile)
4. Univ. of Sao Paulo (Brazil)
5. Univ. Andres Bello, Santiago (Chile); Vatican Observatory, Vatican City (Italy)
6. University of Notre Dame, IN (United States)
7. Eötvös Loránd University (Hungary)
8. Sun Yat-Sen Univ. (China)
9. Space Telescope Science Institute, Baltimore, MD (United States)
10. Univ. Andres Bello, Santiago (Chile)
11. Universidad de La Serena (Chile)

Here, we 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 investigated 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 that 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 likely been produced 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 GCs. 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.

• Research Organization: US Department of Energy (USDOE), Washington, DC (United States). Office of Science, Sloan Digital Sky Survey (SDSS)
• Sponsoring Organization: Alfred P. Sloan Foundation; National Science Foundation (NSF); USDOE Office of Science (SC)
• OSTI ID: 1982298
• Journal Information: Astronomy and Astrophysics, Journal Name: Astronomy and Astrophysics Vol. 658; ISSN 0004-6361
• Publisher: EDP SciencesCopyright Statement
• Country of Publication: United States
• Language: English