The in situ origin of the globular cluster NGC 6388 from abundances of Sc, V, and Zn of a large sample of stars

Carretta, E.; Bragaglia, A.

doi:10.1051/0004-6361/202243211

Cited by 5 publications

(1 citation statement)

References 74 publications

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“…For example, Fernández-Alvar et al (2018) and Recio-Blanco (2018) argued that the α-element abundances and [Si, Ca/Fe], respectively, can distinguish populations with different origins. On the other hand, Carretta & Bragaglia (2022) claimed that iron-peak elements may efficiently identify only the GCs associated with the Sagittarius dwarf galaxy.…”

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confidence: 99%

Heavy element abundances in galactic globular clusters

Schiappacasse-Ulloa,

Lucatello,

Cescutti

et al. 2024

A&A

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Globular clusters are considered key objects for understanding the formation and evolution of the Milky Way. In this sense, the characterisation of their chemical and orbital parameters can provide constraints on chemical evolution models of the Galaxy. We use the heavy element abundances of globular clusters to trace their overall behaviour in the Galaxy, with the aim to analyse potential relations between the hot H-burning and s-process elements. We measured the content of Cu I and s- and r-process elements (Y II, Ba II, La II, and Eu II) in a sample of 210 giant stars in 18 galactic globular clusters from high-quality UVES spectra. These clusters span a broad metallicity range and the sample is the largest that has been uniformly analysed to date, with respect to heavy elements in globular clusters. The Cu abundances did not show a considerable spread in the sample, nor any correlation with Na, indicating that the Na nucleosynthesis process does not affect the Cu abundance. Most GCs closely follow the Cu, Y, Ba, La, and Eu field stars' distribution, revealing a similar chemical evolution. The Y abundances in mid-metallicity regime GCs (-1.10 dex $<$ Fe/H $<$-1.80 dex) display a mildly significant correlation with the Na abundance, which ought to be further investigated. Finally, we do not find any significant difference between the n-capture abundances among GCs with either Galactic and extragalactic origins.

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Section: Introductionmentioning

confidence: 99%

Heavy element abundances in galactic globular clusters

Schiappacasse-Ulloa,

Lucatello,

Cescutti

et al. 2024

A&A

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Chemistry of multiple stellar populations in the mono-metallic, in situ, bulge globular cluster NGC 6388

Carretta¹,

Bragaglia²

2023

A&A

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We present the homogeneous abundance analysis for a combined sample of 185 giants in the bulge globular cluster (GC) NGC 6388. Our results are used to describe the multiple stellar populations and differences or analogies with bulge field stars. Proton-capture elements indicate that a single class of first-generation polluters is sufficient to reproduce both the extreme and intermediate parts of the anti-correlations among light elements O, Na, Mg, and Al, which is at odds with our previous results based on a much smaller sample. The abundance pattern of other species in NGC 6388 closely tracks the trends observed in bulge field stars. In particular, the α-elements, including Si, rule out an accreted origin for NGC 6388, confirming our previous results based on iron-peak elements, chemo-dynamical analysis, and the age-metallicity relation. The neutron-capture elements are generally uniform, although the [Zr/Fe] ratio shows an intrinsic scatter, correlated to Na and Al abundances. Instead, we do not find enhancement in neutron-capture elements for stars whose photometric properties would classify NGC 6388 as a type II GC. Together with the homogeneity in [Fe/H] we found in a previous paper, this indicates we need to better understand the criteria to separate classes of GCs, coupling photometry, and spectroscopy. These results are based on abundances of 22 species (O, Na, Mg, Al, Si, Ca, Ti, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Ba, La, Ce, Nd, and Eu) from UVES spectra sampling proton-, α-, neutron-capture elements, and Fe-peak elements. For 12 species, we also obtain abundances in a large number of giants (up to 150) from GIRAFFE spectra.

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Detailed chemical composition of the globular cluster Sextans A GC-1 on the outskirts of the Local Group

Gvozdenko,

Larsen,

Beasley

et al. 2024

A&A

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The chemical composition of globular clusters (GCs) across the Local Group provides information on chemical abundance trends. Studying GCs in isolated systems in particular provides us with important initial conditions plausibly unperturbed by mergers and tidal forces from the large Local Group spirals. We present a detailed chemical abundance analysis of Sextans A GC-1. The host galaxy, Sextans A, is a low-surface-brightness dwarf irregular galaxy located on the edge of the Local Group. We derive the dynamical mass of the GC together with the mass-to-light ratio and the abundances of the alpha , Fe-peak, and heavy elements. Abundance ratios were determined from the analysis of an optical integrated-light spectrum of Sextans A GC-1, obtained with UVES on the VLT. We apply non-local thermodynamic equilibrium (NLTE) corrections to Mg, Ca, Ti, Fe, and Ni. The GC appears to be younger and more metal-poor than the majority of the GCs of the Milky Way, with an age of 8.6pm 2.7 Gyr and $ Fe/H dex. The calculated dynamical mass is dyn odot $, which results in an atypically high value of the mass-to-light ratio, 4.35pm 1.40 M$_ odot $/L$_ V odot $. Sextans A GC-1 has varying alpha elements -- the Mg abundance is extremely low, Ca and Ti are solar-scaled or mildly enhanced, and Si is enhanced. The measured values are $ Mg/Fe Ca/Fe Ti/Fe and $ Si/Fe which makes the mean alpha abundance (excluding Mg) to be enhanced $ <Si,Ca,Ti>/Fe NLTE The Fe-peak elements are consistent with scaled-solar or slightly enhanced abundances: $ Cr/Fe Mn/Fe Sc/Fe and $ Ni/Fe The heavy elements measured are Ba, Cu, Zn, and Eu. Ba and Cu have sub-solar abundance ratios ($ Ba/Fe and $ Cu/Fe <-0.343$), while Zn and Eu are consistent with their upper limits being solar-scaled and enhanced, $ Zn/Fe <+0.171$ and $ Eu/Fe The composition of Sextans A GC-1 resembles the overall pattern and behaviour of GCs in the Local Group. The anomalous values are the mass-to-light ratio and the depleted abundance of Mg. There is no definite explanation for such an extreme abundance value. Variations in the initial mass function or the presence of an intermediate-mass black hole might explain the high mass-to-light ratio value.

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The in situ origin of the globular cluster NGC 6388 from abundances of Sc, V, and Zn of a large sample of stars

Cited by 5 publications

References 74 publications

Heavy element abundances in galactic globular clusters

Heavy element abundances in galactic globular clusters

Chemistry of multiple stellar populations in the mono-metallic, in situ, bulge globular cluster NGC 6388

Detailed chemical composition of the globular cluster Sextans A GC-1 on the outskirts of the Local Group

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