Chemical study of the metal-rich globular cluster NGC 5927

Mura-Guzmán, Aldo; Villanova, S.; Muñoz, C.; Tang, Baitian

doi:10.1093/mnras/stx2918

Cited by 23 publications

(24 citation statements)

References 54 publications

(100 reference statements)

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“…In particular, we find both Mg and Ti to be higher, [Mg/Fe] NLTE = 0.39 ± 0.04 dex and [Ti/Fe] NLTE = 0.29 ± 0.06 dex, compared to the results of the latter study. For Ti, our higher estimate is likely the consequence of NLTE over-ionisation, as the LTE abundance is [Ti/Fe] LTE = 0.23 ± 0.05 dex, which is consistent with the estimate of [Ti/Fe] = 0.32 ± 0.05 dex from Mura-Guzmán et al (2018). In contrast, the difference in Mg abundance is not related to NLTE.…”

Section: Ngc 2243supporting

confidence: 84%

“…Our average [Mn/Fe] abundance ratio in NGC 5927 is sub-solar [Mn/Fe] NLTE = −0.20 ± 0.03 dex, [Mn/Fe] LTE = −0.34 ± 0.03 dex. This estimate is much lower compared to [Mn/Fe] = −0.09 ± 0.08 dex derived byMura- Guzmán et al (2018), but it is mostly due to the difference of −0.16 in the adopted solar abundance (logA(Mn) = 5.37 dex and logA(Mn) = 5.53 dex, respectively).…”

contrasting

confidence: 61%

“…NGC 5927NGC 5927 is a metal-rich globular cluster located close to the Galactic plane, at an altitude z ∼ 0.6 kpc(Casetti-Dinescu et al 2007). With an age of 12 Gyr(Dotter et al 2010) and metallicity of [Fe/H]∼ −0.5 dex(Mura-Guzmán et al 2018), the cluster is among the oldest metal-rich clusters known in the Galaxy. High-resolution spectroscopy of the cluster revealed the presence of multiple populations, especially prominent in the anti-correlation between Na and OMura- Guzmán et al 2018)…”

mentioning

confidence: 99%

“…Guzmán et al (2018), [Mg/Fe] = 0.27 ± 0.02 dex. It is possible that the differences stem from the differences in atomic data and/or model atmospheres Mura-Guzmán et al (2018).…”

mentioning

confidence: 99%

“…Guzmán et al (2018), [Mg/Fe] = 0.27 ± 0.02 dex. It is possible that the differences stem from the differences in atomic data and/or model atmospheres Mura-Guzmán et al (2018). employ the MOOG code, Kurucz model atmospheres, and linelists fromVillanova & Geisler (2011) and references therein.…”

mentioning

confidence: 99%

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Non-LTE chemical abundances in Galactic open and globular clusters

Kovalev

Bergemann

Ting

et al. 2019

A&A

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Aims. We study the effects of non-local thermodynamic equilibrium (NLTE) on the determination of stellar parameters and abundances of Fe, Mg, and Ti from the medium-resolution spectra of FGK stars. Methods. We extend the Payne fitting approach to draw on NLTE and LTE spectral models. These are used to analyse the spectra of the Gaia-ESO benchmark stars and the spectra of 742 stars in 13 open and globular clusters in the Milky Way: NGC 3532, NGC 5927, NGC 2243, NGC 104, NGC 1851, NGC 2808, NGC 362, M2, MGC 6752, NGC 1904 Results. Our approach accurately recovers effective temperatures, surface gravities, and abundances of the benchmark stars and clusters members. The differences between NLTE and LTE are significant in the metal-poor regime, [Fe/H] −1. The NLTE [Fe/H] values are systematically higher, whereas the average NLTE [Mg/Fe] abundance ratios are ∼ 0.15 dex lower, compared to LTE. Our LTE measurements of metallicities and abundances of stars in Galactic clusters are in a good agreement with the literature. Yet, for most clusters, our study yields the first estimates of NLTE abundances of Fe, Mg and Ti. Conclusions. All clusters investigated in this work are homogeneous in Fe and Ti, with the intra-cluster abundance variations of less then 0.04 dex. NGC 2808, NGC 4833, M2 and M 15 show significant dispersions in [Mg/Fe]. Contrary to common assumptions, the NLTE analysis changes the mean abundance ratios in the clusters, but it does not influence the intra-cluster abundance dispersions.

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Section: Ngc 2243supporting

confidence: 84%

contrasting

confidence: 61%

mentioning

confidence: 99%

“…Guzmán et al (2018), [Mg/Fe] = 0.27 ± 0.02 dex. It is possible that the differences stem from the differences in atomic data and/or model atmospheres Mura-Guzmán et al (2018).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Non-LTE chemical abundances in Galactic open and globular clusters

Kovalev

Bergemann

Ting

et al. 2019

A&A

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Chemical analysis of NGC 6528: one of the most metal-rich bulge globular clusters

Muñoz

Geisler

Villanova

et al. 2018

A&A

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Context. The Bulge Globular Clusters (GCs) are key tracers of this central ancient component of our Galaxy. It is essential to understand their formation and evolution to study that of the bulge, as well as their relationship with the other Galactic GC systems (halo and disk GCs). High resolution spectroscopy is a powerful tool for such studies, allowing us to obtain a detailed chemical characterization and kinematics of the clusters and to compare their chemical patterns with those of their halo and disk counterparts. Aims. Our main goals are to obtain detailed abundances for a sample of seven red giant members of NGC 6528 in order to characterize its chemical composition and study the relationship of this GC with the bulge, and with other bulge, halo and disk GCs. Moreover, we analyze this cluster's behavior associated with the Multiple Populations (MPs) phenomenon. Methods. We obtained the stellar parameters and chemical abundances of light elements (Na, Al), iron-peak elements (V, Cr, Mn, Fe, Co, Ni, Cu), α-elements (O, Mg, Si, Ca, Ti) and heavy elements (Zr, Ba, Eu) in seven red giant members of NGC 6528 using high resolution spectroscopy from FLAMES-UVES. Results. We obtained in six stars of our sample a mean iron content of [Fe/H]=-0.14±0.03 dex, in good agreement with other studies. We found no significant internal iron spread. We detected one candidate variable star, which was excluded from the mean in iron content, we derived a metallicity in this star of [Fe/H]=-0.55±0.04 dex. Moreover, we found no extended O-Na anticorrelation but instead only an intrinsic Na spread. In addition, NGC 6528 does not exhibit a Mg-Al anticorrelation, and no significant spread in either Mg or Al. The α and iron-peak elements show good agreement with the bulge field star trend. The heavy elements are slightly dominated by the r-process. The chemical analysis suggests an origin and evolution similar to that of typical old Bulge field stars. Finally, we find remarkable agreement in the chemical patterns of NGC 6528 and another bulge GC, NGC 6553, suggesting a similar origin and evolution.

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Excess of Ca (and Sc) produced in globular cluster multiple populations: a first census in 77 Galactic globular clusters

Carretta¹,

Bragaglia²

2021

A&A

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Multiple stellar populations in globular clusters (GCs) are distinct by their different abundances of light elements. The abundance anti-correlations point towards a nucleosynthesis origin due to high-temperature H burning, but it remains to be assessed which type of stars altered primordial abundances in GCs. In particular, the regime at very high temperature that shapes the variations in potassium as well as calcium and scandium, which has been detected in a few notable cases such as NGC 2419 and NGC 2808, is still poorly explored. We started a systematic search for excess of Ca (and Sc) in GC stars with respect to the level of unmodified field stars. This method has recently been proven to be highly efficient in revealing the outcome of the proton-capture reactions at very high temperatures. Statistically robust evidence of such excess was found in a small number of GCs (NGC 4833, NGC 6715, NGC 6402, NGC 5296, NGC 5824, and NGC 5139/ω Centauri) that join the previously known two clusters. For the first time we show that NGC 4833 is likely to host anti-correlated K and Mg abundances. All these GCs are among the most massive ones in the Galaxy. We found that the fraction of stars with Ca enhancement at 3σ above the field star distribution is a multivariate function of the GC mass and metallicity, as in other manifestations of the multiple population phenomenon in GCs. We argue that these alterations in only a few GCs can be reproduced by two different channels: either a class of ordinary stars, that is common to all GCs, acts only in particular environments, or an on-off mechanism is generated by the occurrence of a peculiar type of stars (or lack of such stars). Hot bottom-burning in asymptotic giant branch stars in the low-metallicity regime is a good candidate for the first class. Alternatively, a metallicity dependence is also expected for supermassive stars, which are predicted to preferentially form in massive GCs.

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Chemical study of the metal-rich globular cluster NGC 5927

Cited by 23 publications

References 54 publications

Non-LTE chemical abundances in Galactic open and globular clusters

Non-LTE chemical abundances in Galactic open and globular clusters

Chemical analysis of NGC 6528: one of the most metal-rich bulge globular clusters

Excess of Ca (and Sc) produced in globular cluster multiple populations: a first census in 77 Galactic globular clusters

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