Oxygen and zinc abundances in 417 Galactic bulge red giants

Silveira, Carlos Roberto da; Barbuy, B.; Friaça, Amâncio César Santos; Hill, V.; Zoccali, M.; Rafelski, Marc; Gonzalez, O. A.; Minniti, D.; Renzini, A.; Ortolani, S.

doi:10.1051/0004-6361/201730562

Cited by 30 publications

(29 citation statements)

References 88 publications

(204 reference statements)

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“…Were an accreted galaxy to produce a set of GCs with such a low Zn level, we would also expect the presence of debris consisting of accreted field stars with a similarly low Zn pattern, which are not observed here. Stars in the MW actually do reach such a low Zn content, but they are bona fide bulge stars, which are exclusively confined at a metallicity around and above [Fe/H]= 0.0 dex (da Silveira et al 2018), and more than 0.5 dex higher than the metallicity of NGC 6388 or the Sag and LMC stars observed in M21a. The low−α stars in the solar vicinity by Nissen and Schuster (2011) reach a plateau of [Zn/Fe]∼ −0.030 dex (rms=0.057 dex) above [Fe/H]> −1.1 dex (see Fig.…”

Section: Resultsmentioning

confidence: 95%

“…et al (2021b). Empty grey circles are field disc and bulge stars from Adibekyan et al (2012), Battistini and Bensby (2015), Bensby et al (2005Bensby et al ( , 2014Bensby et al ( , 2017, Bihain et al (2004), Brewer et al (2016), da Silveira et al (2018), Delgado-Mena et al (2017, Gratton et al (2003), Ishigaki et al (2012Ishigaki et al ( , 2013, Lomaeva et al (2019), Lucey et al (2019), and Reddy et al (2003. Open blue circles and filled violet circles are the high-α and low-α stars in the local sample by Nissen and Schuster (2011).…”

Section: The Data Setmentioning

confidence: 99%

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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

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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Section: Resultsmentioning

confidence: 95%

Section: The Data Setmentioning

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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“…For that reason, many works have sought N-enhanced stars in field stars and GCs as evidence of second-generation stars (e.g. Barbuy et al 2016;Schiavon et al 2017b;da Silveira et al 2018;Fernández-Trincado et al 2020.…”

Section: Are There Two Stellar Populations?mentioning

confidence: 99%

Photo-chemo-dynamical analysis and the origin of the bulge globular cluster Palomar 6

Souza,

Valentini,

Barbuy

et al. 2021

Preprint

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Context. Palomar 6 is a moderately metal-poor globular cluster projected towards the Galactic bulge. A full analysis of the cluster can give hints on the early chemical enrichment of the Galaxy and a plausible origin of the cluster. Aims. The aim of this study is threefold: a detailed analysis of high-resolution spectroscopic data obtained with the UVES spectrograph at the Very Large Telescope (VLT) at the ESO, the derivation of the age and distance of Palomar 6 from Hubble Space Telescope (HST) photometric data, and an orbital analysis to determine the probable origin of the cluster. Methods. High-resolution spectra of six red giant stars in the direction of Palomar 6 were obtained at the 8m VLT UT2-Kueyen telescope equipped with the UVES spectrograph in FLAMES+UVES configuration. Spectroscopic parameters were derived through excitation and ionisation equilibrium of Fe i and Fe ii lines, and the abundances were obtained from spectrum synthesis. From HST photometric data, the age and distance were derived through a statistical isochrone fitting. Finally, a dynamical analysis was carried out for the cluster assuming two different Galactic potentials. Results. Four stars that are members of Pal 6 were identified in the sample, which gives a mean radial velocity of 174.3±1.6 km s −1 and a mean metallicity of [Fe/H] = −1.10 ± 0.09 for the cluster. We found an enhancement of α-elements 0.29 < [O,Mg,Si,Ca/Fe] < 0.38 and the iron-peak element Ti of [Ti/Fe] ∼ +0.3. The odd-Z elements show a mild enhancement of [Na,Al/Fe] ∼ (+0.3, +0.2). The abundances of both first-and second-peak heavy elements are relatively high, with +0.4 < [Y,Zr/Fe] < +0.60 and +0.4 < [Ba,La/Fe] < +0.5, respectively. The r-element Eu is also relatively high with [Eu/Fe] ∼ +0.6. One member star presents enhancements in N and Al, with [Al/Fe] > +0.30, this being evidence of a second stellar population, further confirmed with the NaON-Al (anti)correlations. For the first time, we derived the age of Pal 6, which resulted to be 12.4 ± 0.9 Gyr. We also found a low extinction coefficient R V = 2.6 for the Pal 6 projection, which is compatible with the latest results for the highly extincted bulge populations. The derived extinction law results in a distance of 7.67 ± 0.19 kpc from the Sun with an A V = 4.21 ± 0.05. The chemical and photometric analyses combined with the orbital-dynamical analyses point out that Pal 6 belongs to the bulge component probably formed in the main-bulge progenitor. Conclusions. The present analysis indicates that the globular cluster Pal 6 is located in the bulge volume and that it was probably formed in bulge in the early stages of the Milky Way formation, and that it shares chemical properties with the family of intermediate metallicity very old clusters M 62, NGC 6522, NGC 6558, and HP 1.

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“…The C, N, and O abundances were revised in Friaça & Barbuy (2017). The iron-peak elements Mn and Zn were studied in Barbuy et al (2013Barbuy et al ( , 2015 and da Silveira et al (2018), and heavy elements in van der Swaelmen et al (2016). In summary, the abundances of C, N, O, Na, Mg, Al, Mn, Zn, and heavy elements were derived.…”

Section: Observationsmentioning

confidence: 99%

Cobalt and copper abundances in 56 Galactic bulge red giants

Ernandes

Barbuy

Friaça

et al. 2020

A&A

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Context. The Milky Way bulge is an important tracer of the early formation and chemical enrichment of the Galaxy. The abundances of different iron-peak elements in field bulge stars can give information on the nucleosynthesis processes that took place in the earliest supernovae. Cobalt (Z = 27) and copper (Z = 29) are particularly interesting. Aims. We aim to identify the nucleosynthesis processes responsible for the formation of the iron-peak elements Co and Cu. Methods. We derived abundances of the iron-peak elements cobalt and copper in 56 bulge giants, 13 of which were red clump stars. High-resolution spectra were obtained using FLAMES-UVES at the ESO Very Large Telescope by our group in 2000–2002, which appears to be the highest quality sample of optical high-resolution data on bulge red giants obtained in the literature to date. Over the years we have derived the abundances of C, N, O, Na, Al, Mg; the iron-group elements Mn and Zn; and neutron-capture elements. In the present work we derive abundances of the iron-peak elements cobalt and copper. We also compute chemodynamical evolution models to interpret the observed behaviour of these elements as a function of iron. Results. The sample stars show mean values of [Co/Fe] ~ 0.0 at all metallicities, and [Cu/Fe] ~ 0.0 for [Fe/H] ≥−0.8 and decreasing towards lower metallicities with a behaviour of a secondary element. Conclusions. We conclude that [Co/Fe] varies in lockstep with [Fe/H], which indicates that it should be produced in the alpha-rich freezeout mechanism in massive stars. Instead [Cu/Fe] follows the behaviour of a secondary element towards lower metallicities, indicating its production in the weak s-process nucleosynthesis in He-burning and later stages. The chemodynamical models presented here confirm the behaviour of these two elements (i.e. [Co/Fe] vs. [Fe/H] ~constant and [Cu/Fe] decreasing with decreasing metallicities).

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Oxygen and zinc abundances in 417 Galactic bulge red giants

Cited by 30 publications

References 88 publications

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

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

Photo-chemo-dynamical analysis and the origin of the bulge globular cluster Palomar 6

Cobalt and copper abundances in 56 Galactic bulge red giants

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