The potassium abundance in the globular clusters NGC 104, NGC 6752 and NGC 6809

Mucciarelli, A.; Merle, Thibault; Bellazzini, M.

doi:10.1051/0004-6361/201730410

Cited by 34 publications

(39 citation statements)

References 54 publications

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“…For them, the average abundance ratios obtained by Carretta et al (2013) The sample-averaged K abundance obtained in the study of 144 RGB stars in 47 Tuc by Mucciarelli et al (2017), [K/Fe] 1D NLTE = −0.12 ±0.08, is somewhat lower than that determined in Paper I, [K/Fe] RGB = 0.05 ± 0.13. This difference may be a result of the different microturbulent velocties used in the two studies: the sample-averaged value in Mucciarelli et al (2017) is ξ t = 1.66 km/s while in our analysis we used 1.5 km/s. Our tests show that the difference of 0.16 km/s in ξ t would lead to an ∼ 0.13 dex decrease in the average [K/Fe] ratio determined in Paper I using RGB stars.…”

Section: Average Abundances and Intrinsic Abundance Spreads In 47 Tucmentioning

confidence: 66%

“…These findings support our earlier results obtained in the analysis of Na, Mg, and K abundances in 32 RGB stars in Paper I, where we found no statistically significant relations in the abundance-abundance, abundance-distance, and abundanceabsolute radial velocity planes. On the other hand, a study of 144 RGB stars in 47 Tuc by Mucciarelli et al (2017) revealed statistically significant [K/Fe] − [Na/Fe] correlation and [K/Fe] − [O/Fe] anti-correlation (in the same study, such correlations were also detected in the globular cluster NGC 6752). In their analysis, Mucciarelli et al (2017) used Spearman's nonparametric rank-order correlation coefficients, r s , and computed the two-tailed probability, p, that in a given dataset r s could attain a value that is equal to or larger than its measured value.…”

Section: Relations Between the Abundances Of Light Elements And Evolumentioning

confidence: 79%

“…The determined uncertainties are provided in Table 4. In order to estimate the size of the possible intrinsic spread in the 1D NLTE abundances of Li, O, Na, Mg, and K, we followed the procedure used in Paper I, which is based on the prescription of Mucciarelli et al (2012Mucciarelli et al ( , 2015 that the authors applied to study the K abundance spreads in NGC 2419 and NGC 2808, and, later, also in 47 Tuc (Mucciarelli et al 2017…”

Section: D-1d Abundance Corrections For Mg and Kmentioning

confidence: 99%

“…To our knowledge, the only studies of K abundance in 47 Tuc that have been carried out until now are those by Carretta et al (2013) and Mucciarelli et al (2017). The average 1D NLTE potassium-to-iron abundance ratios obtained by Carretta et al (2013) in three TO and nine SGB stars were [K/Fe] TO = 0.19 ± 0.07 and [K/Fe] SGB = 0.12 ± 0.12, respectively (the error is RMS deviation due to star-to-star abundance variation).…”

Section: Average Abundances and Intrinsic Abundance Spreads In 47 Tucmentioning

confidence: 99%

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Abundances of Mg and K in the atmospheres of turn-off starsin Galactic globular cluster 47 Tucanae

Černiauskas¹,

Kučinskas²,

Klevas³

et al. 2018

A&A

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Aims. We determined abundances of Mg and K in the atmospheres of 53 (Mg) and 75 (K) turn-off (TO) stars of the Galactic globular cluster 47 Tuc. The obtained abundances, together with those of Li, O, and Na that we had earlier determined for the same sample of stars, were used to search for possible relations between the abundances of K and other light elements, Li, O, Na, and Mg, as well as the connections between the chemical composition of TO stars and their kinematical properties. Methods. Abundances of Mg and K were determined using archival high resolution VLT FLAMES/GIRAFFE spectra, in combination with the one-dimensional (1D) non-local thermodynamic equilibrium (NLTE) spectral synthesis methodology. Spectral line profiles were computed with the MULTI code, using 1D hydrostatic ATLAS9 stellar model atmospheres. We also utilized three-dimensional (3D) hydrodynamical CO 5 BOLD and 1D hydrostatic LHD model atmospheres for computing 3D-1D LTE abundance corrections for the spectral lines of Mg and K, in order to assess the influence of convection on their formation in the atmospheres of TO stars. Results. The determined average abundance-to-iron ratios and their root mean square (RMS) variations due to star-to-star abundance spreads were [Mg/Fe] 1D NLTE = 0.47 ± 0.12, and [K/Fe] 1D NLTE = 0.39 ± 0.09. Although the data suggest the possible existence of a weak correlation in the [K/Fe]-[Na/Fe] plane, its statistical significance is low. No statistically significant relations between the abundance of K and other light elements were detected. Also, we did not find any significant correlations or anti-correlations between the [Mg/Fe] and [K/Fe] ratios and projected distance from the cluster center. Similarly, no relations between the absolute radial velocities of individual stars and abundances of Mg and K in their atmospheres were detected. The 3D-1D abundance corrections were found to be small (≤ 0.1 dex) for the lines of Mg and K used in this study, thus indicating that the influence of convection on their formation is small.

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Section: Average Abundances and Intrinsic Abundance Spreads In 47 Tucmentioning

confidence: 66%

Section: Relations Between the Abundances Of Light Elements And Evolumentioning

confidence: 79%

Section: D-1d Abundance Corrections For Mg and Kmentioning

confidence: 99%

Section: Average Abundances and Intrinsic Abundance Spreads In 47 Tucmentioning

confidence: 99%

See 2 more Smart Citations

Abundances of Mg and K in the atmospheres of turn-off starsin Galactic globular cluster 47 Tucanae

Černiauskas¹,

Kučinskas²,

Klevas³

et al. 2018

A&A

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show abstract

“…A targeted search for [K/Fe] in other globular clusters (NGC 6752, NGC 6121, NGC 1904, NGC 104, NGC 6397, NGC 7099, and ω Centauri) and field stars concluded that all K abundance ratios fell within the bounds of the Mg-normal population in NGC 2419 (Carretta et al 2013), and no correlations between Mg and K were observed. Recent work byČerniauskas et al (2017) searched for unusual abundance patterns in Mg and K in NGC 104 by deriving abundances using 2dF/HERMES spectra, and a more comprehensive study involving over 400 stars in NGC 104, NGC 6752, and NGC 6809 by Mucciarelli et al (2017) using FLAMES spectra (Černiauskas et al 2017 both found no correlations between Mg and K, and no significant intrinsic spreads in either Mg or K. NGC 2808 is the only cluster, other than NGC 2419, where an anticorrelation between Mg and K has been observed. All four of NGC 2808's known Mg-depleted stars show an anti-correlation with K (Mucciarelli et al 2015), although the amplitude of these abundance ratios is far weaker than those found in NGC 2419.…”

Section: Introductionmentioning

confidence: 99%

On the discovery of K-enhanced and possibly Mg-depleted stars throughout the Milky Way

Kemp

Casey

Miles

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Stars with unusual elemental abundances offer clues about rare astrophysical events or nucleosynthetic pathways. Stars with significantly depleted magnesium and enhanced potassium ([Mg/Fe] < −0.5; [K/Fe] > 1) have to date only been found in the massive globular cluster NGC 2419 and, to a lesser extent, NGC 2808. The origin of this abundance signature remains unknown, as does the reason for its apparent exclusivity to these two globular clusters. Here we present 112 field stars, identified from 454,180 LAMOST giants, that show significantly enhanced [K/Fe] and possibly depleted [Mg/Fe] abundance ratios. Our sample spans a wide range of metallicities (−1.5 < [Fe/H] < 0.3), yet none show abundance ratios of [K/Fe] or [Mg/Fe] that are as extreme as those observed in NGC 2419. If confirmed, the identified sample of stars represents evidence that the nucleosynthetic process producing the anomalous abundances ratios of [K/Fe] and [Mg/Fe] probably occurs at a wide range of metallicities. This would suggest that pollution scenarios that are limited to early epochs (such as Population III supernovae) are an unlikely explanation, although they cannot be ruled out entirely. This sample is expected to help guide modelling attempts to explain the origin of the Mg-K abundance signature.

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Absorption caused by potassium molecules in astrophysical plasmas: Data needed for modeling

Srećković

Dimitrijević

Ignjatović

2023

Advances in Space Research

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The potassium abundance in the globular clusters NGC 104, NGC 6752 and NGC 6809

Cited by 34 publications

References 54 publications

Abundances of Mg and K in the atmospheres of turn-off starsin Galactic globular cluster 47 Tucanae

Abundances of Mg and K in the atmospheres of turn-off starsin Galactic globular cluster 47 Tucanae

On the discovery of K-enhanced and possibly Mg-depleted stars throughout the Milky Way

Absorption caused by potassium molecules in astrophysical plasmas: Data needed for modeling

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