Iron-peak elements Sc, V, Mn, Cu, and Zn in Galactic bulge globular clusters

Ernandes, H.; Barbuy, B.; Alves-Brito, Alan; Friaça, Amâncio César Santos; Siqueira-Mello, C.; Allen, D. M.

doi:10.1051/0004-6361/201731708

Cited by 32 publications

(54 citation statements)

References 102 publications

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“…If the scatter is real, it may indicate that the bulge composition evolved much more inhomogeneously than that of the Galactic disk. However, this scatter is neither confirmed by Ernandes et al (2018) or our results, which suggests that it more likely comes from measurement uncertainty.…”

Section: The Evolutionary Trend Of [Cu/fe] In the Bulgecontrasting

confidence: 96%

“…We note that there are no obvious differences in copper abundances between our sample and those from Reddy et al (2006). We also find, in good agreement with Ernandes et al (2018), that the bulge shows a similar [Cu/Fe] trend with that of the Galactic disk.…”

Section: The Evolutionary Trend Of [Cu/fe] In the Bulgesupporting

confidence: 88%

“…The LTE and NLTE results of each star are shown in the last two columns, respectively. We present the [Cu/Fe] ratios versus [Fe/H] for our NLTE calculations (black filled circles), together with LTE results from Reddy et al (2006) of the Galactic disk (blue asterisks), Johnson et al (2014; green filled circles) and Ernandes et al (2018; red open diamonds) of the bulges in Figure 6. It is clear that our calculations tend to be less enhanced than those by Johnson et al (2014) and exhibit a discrepant [Cu/Fe] trend.…”

Section: The Evolutionary Trend Of [Cu/fe] In the Bulgementioning

confidence: 99%

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NLTE Analysis of Copper Abundances in the Galactic Bulge Stars

Shi

Yan

2019

ApJ

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Based on the medium-high resolution (R ∼ 20,000), modest signal-to-noise ratio (S/N70) FLAMES-GIRAFFE spectra, we investigated the copper abundances of 129 red giant branch stars in the Galactic bulge with [Fe/H] from −1.14 to 0.46 dex. The copper abundances are derived from both local thermodynamic equilibrium (LTE) and nonlocal thermodynamic equilibrium (NLTE) with the spectral synthesis method. We find that the NLTE effects for Cu I lines show a clear dependence on metallicity, and they gradually increase with decreasing [Fe/H] for our sample stars. Our results indicate that the NLTE effects of copper are important not only for metal-poor stars but also for supersolar metal-rich ones and the LTE results underestimate the Cu abundances. We note that the [Cu/Fe] trend of the bulge stars is similar to that of the Galactic disk stars spanning the metallicity range of −1.14<[Fe/H]<0.0 dex, and the [Cu/Fe] ratios increase with increasing metallicity when [Fe/H] is from ∼−1.2 to ∼−0.5 dex, favoring a secondary (metallicity-dependent) production of Cu.

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Section: The Evolutionary Trend Of [Cu/fe] In the Bulgecontrasting

confidence: 96%

Section: The Evolutionary Trend Of [Cu/fe] In the Bulgesupporting

confidence: 88%

Section: The Evolutionary Trend Of [Cu/fe] In the Bulgementioning

confidence: 99%

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NLTE Analysis of Copper Abundances in the Galactic Bulge Stars

Shi

Yan

2019

ApJ

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“…Barbuy et al 2018a;Bensby et al 2017;Friaça & Barbuy 2017;McWilliam 2016). The iron-peak elements were derived for these stars in Ernandes et al (2018). As for the heavy elements, we compared the present results with available literature abundances of heavy elements in bulge field stars, and results for NGC 6558 from Barbuy et al (2007), and other globular clusters: a) Johnson et al (2012) derived abundances of Eu in common with the present element abundance derivation.…”

Section: Discussionmentioning

confidence: 81%

High-resolution abundance analysis of four red giants in the globular cluster NGC 6558

Barbuy¹,

Muniz²,

Ortolani³

et al. 2018

A&A

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Context. NGC 6558 is a bulge globular cluster with a blue horizontal branch (BHB), combined with a metallicity of [Fe/H]≈-1.0. It is similar to HP 1 and NGC 6522, which could be among the oldest objects in the Galaxy. Element abundances in these clusters could reveal the nature of the first supernovae. Aims. We aim to carry out detailed spectroscopic analysis for four red giants of NGC 6558, in order to derive the abundances of the light elements C, N, O, Na, Al, the α-elements Mg, Si, Ca, Ti, and the heavy elements Y, Ba, and Eu. Methods. High-resolution spectra of four stars with FLAMES-UVES@VLT UT2-Kueyen were analysed. Spectroscopic parameter-derivation was based on excitation and ionization equilibrium of Fe I and Fe II.Results. This analysis results in a metallicity of [Fe/H] = −1.17 ± 0.10 for NGC 6558. We find the expected α-element enhancements in O and Mg with [O/Fe]=+0.40, [Mg/Fe]=+0.33, and low enhancements in Si and Ca. Ti has a moderate enhancement of [Ti/Fe]=+0.22. The r-element Eu appears very enhanced with a mean value of [Eu/Fe]=+0.63. Ba appears to have a solar abundance ratio relative to Fe. Conclusions. NGC 6558 shows an abundance pattern that could be typical of the oldest inner bulge globular clusters, together with the pattern in the similar clusters NGC 6522 and HP 1. They show low abundances of the odd-Z elements Na and Al, and of the explosive nucleosynthesis α-elements Si, Ca, and Ti. The hydrostatic burning α-elements O and Mg are normally enhanced as expected in old stars enriched with yields from core-collapse supernovae, and the iron-peak elements Mn, Cu, Zn show low abundances, which is expected for Mn and Cu, but not for Zn. Finally, the cluster trio NGC 6558, NGC 6522, and HP 1 show similar abundance patterns.

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“…Figures C.1 and C.2 show the fits to the spectra of the Sun, Arcturus, and µ Leo. The Cu i atomic parameters and fits to these reference stars were already extensively discussed in Ernandes et al (2018).…”

Section: Abundance Analysismentioning

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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Iron-peak elements Sc, V, Mn, Cu, and Zn in Galactic bulge globular clusters

Cited by 32 publications

References 102 publications

NLTE Analysis of Copper Abundances in the Galactic Bulge Stars

NLTE Analysis of Copper Abundances in the Galactic Bulge Stars

High-resolution abundance analysis of four red giants in the globular cluster NGC 6558

Cobalt and copper abundances in 56 Galactic bulge red giants

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