Chemical abundances in the metal-intermediate GC NGC 6723

Crestani, Juliana; Alves-Brito, Alan; Bono, G.; Puls, Arthur Alencastro; Alonso-García, J.

doi:10.1093/mnras/stz1674

Cited by 18 publications

(24 citation statements)

References 86 publications

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“…Moreover, it is important to notice that the possible absence of a spread in Al appears consistent with expectations of AGB nucleosynthesis (Ventura & D'Antona 2008;Ventura et al 2016;Karakas & Lattanzio 2014;Crestani et al 2019), and its expected low production in relatively high metallicity GC stars such as observed in Ton 2. Figure 5(a) shows no clear signs of an Mg-Al anti-correlation in Ton 2, which is consistent with no net production of these elements, rather, just the result of the conversion of Mg into Al during the Mg-Al cycle (e.g., Pancino et al 2017).…”

Section: The Odd-z Element: Alsupporting

confidence: 80%

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

Fernández-Trincado,

Villanova,

Geisler

et al. 2021

Preprint

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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.

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Section: The Odd-z Element: Alsupporting

confidence: 80%

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

Fernández-Trincado,

Villanova,

Geisler

et al. 2021

Preprint

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“…For nickel (Ni), UKS 1 has [Ni/Fe] = 0.03 ± 0.05 (with a star-to-star spread ∼0.15 dex) similar to that observed in other GCs, for example NGC 6723 (Crestani et al 2019), and is slightly enhanced, similar to bulge field stars at metallicities above [Fe/H] ∼ −1 dex (e.g. Johnson et al 2014;Bensby et al 2017).…”

Section: The Fe-peak Elements: Fe and Nisupporting

confidence: 68%

“…Overall, UKS 1 displays slightly higher α-element enhancement, a possible signature of the fast enrichment provided by supernovae (SNe) II events, as expected in old GCs (see, e.g. Crestani et al 2019). Origlia et al (2005) successfully measured [O/Fe], [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe] abundances for UKS 1.…”

Section: The Light-elements: C and Nmentioning

confidence: 58%

The enigmatic globular cluster UKS 1 obscured by the bulge: H-band discovery of nitrogen-enhanced stars

Fernández-Trincado

Minniti

Beers

et al. 2020

A&A

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The presence of nitrogen-enriched stars in globular clusters provides key evidence for multiple stellar populations (MPs), as has been demonstrated with globular cluster spectroscopic data towards the bulge, disk, and halo. In this work, we employ the VVV Infrared Astrometric Catalogue (VIRAC) and the DR16 SDSS-IV release of the APOGEE survey to provide the first detailed spectroscopic study of the bulge globular cluster UKS 1. Based on these data, a sample of six selected cluster members was studied. We find the mean metallicity of UKS 1 to be [Fe/H] = −0.98 ± 0.11, considerably more metal-poor than previously reported, and a negligible metallicity scatter, typical of that observed by APOGEE in other Galactic globular clusters. In addition, we find a mean radial velocity of 66.1 ± 12.9 km s−1, which is in good agreement with literature values, within 1σ. By selecting stars in the VIRAC catalogue towards UKS 1, we also measure a mean proper motion of (μαcos(δ), μδ) = (−2.77 ± 0.23, −2.43 ± 0.16) mas yr−1. We find strong evidence for the presence of MPs in UKS 1, since four out of the six giants analysed in this work have strong enrichment in nitrogen ([N/Fe] ≳ +0.95) accompanied by lower carbon abundances ([C/Fe] ≲ −0.2). Overall, the light- (C, N), α- (O, Mg, Si, Ca, Ti), Fe-peak (Fe, Ni), Odd-Z (Al, K), and the s-process (Ce, Nd, Yb) elemental abundances of our member candidates are consistent with those observed in globular clusters at similar metallicity. Furthermore, the overall star-to-star abundance scatter of elements exhibiting the multiple-population phenomenon in UKS 1 is typical of that found in other global clusters (GCs), and larger than the typical errors of some [X/Fe] abundances. Results from statistical isochrone fits in the VVV colour-magnitude diagrams indicate an age of 13.10−1.29+0.93 Gyr, suggesting that UKS 1 is a fossil relic in the Galactic bulge.

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“…3 the AMR of MW GCs, which is an additional diagnostic plot required to solve the degeneracy concern- and [Zn/Fe] for metal-rich GCs in the literature (blue filled circles are for GCs of the main progenitor, either M-B or M-D; green circles are for Sagittarius GCs, and red circles are for all other accreted GCs of the L-E, H-E, H99, GSE, and SEQ groups) compared to the field star distributions. Abundances for GCs are from Carretta (2015), Carretta et al (2004), Cohen (2004, Crestani et al (2019), Feltzing et al (2009), Gratton et al (2006Gratton et al ( , 2007, Ivans et al (1999), Massari et al (2017), Monaco et al (2018), Muñoz et al (2017Muñoz et al ( , 2018Muñoz et al ( , 2020 ing the origin of NGC 6388. We used cluster ages for 96 GCs, with orbital parameters in Savino and Posti (2019), assembled and homogenised by Kruijssen et al (2019).…”

Section: Discussionmentioning

confidence: 99%

“…Mean abundance ratios [Sc/Fe], [V/Fe],and [Zn/Fe] for metal-rich GCs in the literature (blue filled circles are for GCs of the main progenitor, either M-B or M-D; green circles are for Sagittarius GCs, and red circles are for all other accreted GCs of the L-E, H-E, H99, GSE, and SEQ groups) compared to the field star distributions. Abundances for GCs are from Carretta (2015),Carretta et al (2004Carretta et al ( , 2011,Cohen (2004),Crestani et al (2019),Feltzing et al (2009),Gratton et al (2006Gratton et al ( , 2007,Ivans et al (1999),Massari et al (2017),Monaco et al (2018),Muñoz et al (2017Muñoz et al ( , 2018Muñoz et al ( , 2020,Mura- Guzmàn et al (2018), O'Connell et al (2011,Puls et al (2018), Ramìrez andCohen (2002),Sakari et al (2011),Sbordone et al (2007), andYong et al (2014).…”

mentioning

confidence: 99%

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

Carretta¹,

Bragaglia²

2022

A&A

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Chemical tagging of globular clusters (GCs) is often done using abundances of α−elements. The iron-peak elements Sc, V, and in particular Zn were proposed as an alternative to α−elements to tag accreted GCs in the metal-rich regime, where the dwarf galaxy Sagittarius and its GCs show peculiarly marked under-abundances of these heavier species with respect to Milky Way stars. A handful of stars in NGC 6388 was used to suggest an accreted origin for this GC, contradicting the results from dynamics. We tested the efficiency of the iron-peak method by using large samples of stars in NGC 6388, compared to thousands of field stars in the disc and the bulge of the Milky Way. Our abundance ratios of Sc (185 stars) and V (35 stars) for NGC 6388 are within about 1.5σ from the average for the field stars with a similar metallicity, and they are in perfect agreement for Zn (31 stars), claimed to be the most sensitive element concerning the accretion pattern. Moreover, the chemo-dynamical plots, coupled to the bifurcated age-metallicity relation of GCs in the Galaxy, clearly rule out any association of NGC 6388 to the groups of accreted GCs. Using a large set of GC abundances from the literature, we also show that the new method with Sc, V, and Zn seems to be efficient in picking up GCs related to the Sagittarius dwarf galaxy. Whether this is also generally true for accreted GCs seems to be less evident, and it should be verified with larger and homogeneous samples of stars both in the field and in GCs.

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Chemical abundances in the metal-intermediate GC NGC 6723

Cited by 18 publications

References 86 publications

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

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

The enigmatic globular cluster UKS 1 obscured by the bulge: H-band discovery of nitrogen-enhanced stars

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

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