Abundances of Na, Mg, and K in the atmospheres of red giant branch stars of Galactic globular cluster 47 Tucanae

Černiauskas, A.; Kučinskas, A.; Klevas, J.; Prakapavičius, D.; Коротин, С. А.; Bonifacio, P.; Ludwig, H.‐G.; Caffau, E.; Steffen, M.

doi:10.1051/0004-6361/201630305

Cited by 23 publications

(8 citation statements)

References 66 publications

(90 reference statements)

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“…NGC 104 (47 Tuc) is among the brightest and most well-studied clusters in the Milky Way (e.g. Anderson et al 2009;Campos et al 2018;Milone et al 2012;Lapenna et al 2014;Cordero et al 2014;Thygesen et al 2014;Černiauskas et al 2017). The recent estimate of the distance to the cluster is d = 4.45 kpc (Chen et al 2018), which was obtained on the basis of Gaia DR2 parallaxes.…”

Section: Ngc 104 (47 Tuc)mentioning

confidence: 99%

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 104 (47 Tuc)mentioning

confidence: 99%

Non-LTE chemical abundances in Galactic open and globular clusters

Kovalev

Bergemann

Ting

et al. 2019

A&A

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“…The Mg i lines we selected to derive the Mg abundance are formed close to the LTE condition. In the case of Mg, we used the model atom from Mishenina et al (2004), then updated by Cerniauskas et al (2017). It consisted of 84 levels of Mg i, 12 levels of Mg ii, and the ground state of Mg iii.…”

Section: The Other Elementsmentioning

confidence: 99%

Systematic investigation of chemical abundances derived using IR spectra obtained with GIANO

Caffau

Bonifacio

Oliva

et al. 2019

A&A

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Context. Detailed chemical abundances of Galactic stars are needed in order to improve our knowledge of the formation and evolution of our galaxy, the Milky Way. Aims. We took advantage of the GIANO archive spectra to select a sample of Galactic disc stars in order to derive their chemical inventory and to compare the abundances we derived from these infrared spectra to the chemical pattern derived from optical spectra. Methods. We analysed high-quality spectra of 40 stars observed with GIANO. We derived the stellar parameters from the photometry and the Gaia data-release 2 (DR2) parallax; the chemical abundances were derived with the code MyGIsFOS. For a subsample of stars we compared the chemical pattern derived from the GIANO spectra with the abundances derived from optical spectra. We derived P abundances for all 40 stars, increasing the number of Galactic stars for which phosphorus abundance is known. Results. We could derive abundances of 14 elements, 8 of which are also derived from optical spectra. The comparison of the abundances derived from infrared and optical spectra is very good. The chemical pattern of these stars is the one expected for Galactic disc stars and is in agreement with the results from the literature. Conclusions. GIANO is providing the astronomical community with an extremely useful instrument, able to produce spectra with high resolution and a wide wavelength range in the infrared. 1 http://atlas.obs-hp.fr/sophie/ 2 V J = V T − 0.090 * (B − V) T z = B T − V T − 0.90 (B − V) J = (B T − V T ) − 0.115 − 0.229z + 0.043z 3

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“…Although GAIA EDR3 photometry for the target stars was also available, we decided to use photometric data from Bergbusch & Stetson (2009) in order to retain homogeneity and consistency with our previous studies of 47 Tuc (see e.g. Dobrovolskas et al 2014;Černiauskas et al 2017). The average difference between the effective temperatures determined using (V − I) colour indices and those obtained from the GAIA EDR3 photometry and colour-effective temperature calibration from Mucciarelli et al (2021) is ∼ −59 K and does not affect the results obtained in this study.…”

Section: Observational Data and Atmospheric Parametersmentioning

confidence: 99%

Abundance of zirconium in the globular cluster 47 Tuc: a possible Zr-Na correlation?

Kolomiecas,

Dobrovolskas,

Kučinskas

et al. 2021

Preprint

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Aims. We determined abundances of Na and Zr in the atmospheres of 237 RGB stars in Galactic globular cluster (GGC) 47 Tuc (NGC 104), with a primary objective of investigating possible differences between the abundances of Zr in the first generation (1P) and second generation (2P) stars. Methods. For the abundance analysis, we used archival UVES/GIRAFFE spectra obtained during three different observing programmes. Abundances were determined from two Na i and three Zr i lines, using 1D hydrostatic ATLAS9 model atmospheres. The target stars for the abundance analysis were limited to those with 4200 ≤ T eff ≤ 4800 K. This is the largest sample of GGC stars in which Na and Zr abundances have been studied so far. Results. While our mean [Na/Fe] and [Zr/Fe] ratios agree well with those determined in the earlier studies, we find a weak but statistically significant correlation in the [Zr/Fe] − [Na/Fe] plane. A comparison of the mean [Zr/Fe] abundance ratios in the 1P and 2P stars suggests a small but statistically significant Zr over-abundance in the 2P stars, ∆[Zr/Fe] 2P−1P ≈ +0.06 dex. Also, our analysis shows that stars enriched in both Zr and Na are more centrally concentrated. However, we find no correlation between their distance from the cluster centre and their full spatial velocity, as indicated by the velocity dispersions at different mean values of [Zr/Fe] and [Na/Fe]. While there may be some influence of CN line blends on the determined Zr abundances, it seems very unlikely that the detected Zr-Na correlation, for the slightly higher Zr abundances in the 2P stars, would be caused by the CN blending alone. Conclusions. The obtained results indicate that, in 47 Tuc, some amount of Zr should have been synthesised by the same polluters that enriched 2P stars with the light elements. While sizeable amounts of Zr may be synthesised by both AGB stars (M ∼ 1.5 − 5 M ⊙ ) and massive rotating stars (M ∼ 12 − 25 M ⊙ , v rot > 150 km s −1 ), our data alone do not allow us to distinguish which of the two scenarios, or whether or not a combination of both, could have operated in this GGC.

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Abundances of Na, Mg, and K in the atmospheres of red giant branch stars of Galactic globular cluster 47 Tucanae

Cited by 23 publications

References 66 publications

Non-LTE chemical abundances in Galactic open and globular clusters

Non-LTE chemical abundances in Galactic open and globular clusters

Systematic investigation of chemical abundances derived using IR spectra obtained with GIANO

Abundance of zirconium in the globular cluster 47 Tuc: a possible Zr-Na correlation?

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