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arXiv · 2406.07180

Detailed chemical abundances of the globular cluster Terzan 6 in the inner bulge

C. Fanelli·L. Origlia·A. Mucciarelli·F. R. Ferraro·R. M. Rich·B. Lanzoni·D. Massari·C. Pallanca·E. Dalessandro·M. Loriga
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Abstract

We used near-infrared spectroscopy at medium-high resolution (R=8,000$-$25,000) to perform the first comprehensive chemical study of the intermediate luminosity bulge globular cluster Terzan~6. We derived detailed abundances and abundance patterns of 27 giant stars, likely members of Terzan~6, based on their accurate Hubble Space Telescope proper motions and line-of-sight radial velocities. From the spectral analysis of these stars, we determined an average heliocentric radial velocity of 143.3$\pm$1.0 km s$^{-1}$ with a velocity dispersion of 5.1$\pm$0.7 km s$^{-1}$ and an average [Fe/H]=$-0.65\pm0.01$ and a low 1$\sigma$ dispersion of 0.03 dex. We also measured some depletion of [Mn/Fe] with respect to the solar-scaled values and enhancement of for [Ca/Fe], [Si/Fe], [Mg/Fe], [Ti/Fe], [O/Fe], [Al/Fe], [Na/Fe], and, to a lower extent, for [K/Fe], consistent with previous measurements of other bulge globular clusters and favoring the scenario of a rapid bulge formation and chemical enrichment. Some spread in the light element abundances suggest the presence of first- and second-generation stars, typical of genuine globulars. Finally, we measured some depletion of carbon and low $\rm ^{12}C/^{13}C$ isotopic ratios, as in previous studies of field and cluster bulge giants, indicating that extra-mixing mechanisms should be at work during the post main sequence evolution in the high metallicity regime as well.

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C. Fanelli, L. Origlia, A. Mucciarelli, F. R. Ferraro, R. M. Rich, B. Lanzoni, D. Massari, C. Pallanca, E. Dalessandro, M. Loriga. 2024-06-11. Detailed chemical abundances of the globular cluster Terzan 6 in the inner bulge. https://arxiv.org/abs/2406.07180

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