2022A&A...657A..33A


Query : 2022A&A...657A..33A

2022A&A...657A..33A - Astronomy and Astrophysics, volume 657A, 33-33 (2022/1-1)

Lithium on the lower red giant branch of five Galactic globular clusters.

AGUILERA-GOMEZ C., MONACO L., MUCCIARELLI A., SALARIS M., VILLANOVA S. and PANCINO E.

Abstract (from CDS):

Context. Lithium is one of the few elements produced during Big Bang nucleosynthesis in the early universe. Moreover, its fragility makes it useful as a proxy for stellar environmental conditions. As such, the lithium abundance in old systems is at the core of various astrophysical investigations. Aims. Stars on the lower red giant branch are key to studies of globular clusters where main sequence stars are too faint to be observed. We use these stars to analyze the initial Li content of the clusters and compare it to cosmological predictions, to measure spreads in Li between different stellar populations, and to study signs of extra depletion in these giants. Methods. We used the GIRAFFE spectra to measure the lithium and sodium abundances of lower red giant branch stars in five globular clusters. These cover an extensive range in metallicity, from [Fe/H] ∼ -0.7 to [Fe/H] ∼ -2.3 dex. Results. We find that the lithium abundance in these lower red giant branch stars forms a plateau, with values from A(Li)NLTE = 0.84 to 1.03 dex, showing no clear correlation with metallicity. When using stellar evolutionary models to calculate the primordial abundance of these clusters, we recover values of A(Li)NLTE = 2.1 - 2.3 dex, consistent with the constant value observed in warm metal-poor halo stars, namely the Spite plateau. Additionally, we find no difference in the lithium abundance of first and second population stars in each cluster. We also report the discovery of a Li-rich giant in the cluster NGC 3201, with A(Li)NLTE = 1.63 ±0.18 dex, where the enrichment mechanism is probably pollution from external sources.

Abstract Copyright: © ESO 2021

Journal keyword(s): globular clusters: general - stars: abundances - primordial nucleosynthesis - stars: chemically peculiar

VizieR on-line data: <Available at CDS (J/A+A/657/A33): tablea1.dat>

Status at CDS : Tables of objects will be appraised for possible ingestion in SIMBAD.

Simbad objects: 23

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Number of rows : 23
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3781 0
2 NGC 362 GlC 01 03 14.26 -70 50 55.6     6.58     ~ 1031 0
3 NGC 1261 GlC 03 12 16.21 -55 12 58.4     8.63     ~ 488 0
4 M 79 GlC 05 24 10.59 -24 31 27.3     8.16     ~ 780 0
5 NGC 2808 GlC 09 12 03.10 -64 51 48.6           ~ 1364 0
6 NGC 3201 GlC 10 17 36.82 -46 24 44.9           ~ 818 0
7 M 68 GlC 12 39 27.98 -26 44 38.6     7.96     ~ 952 0
8 NGC 5053 GlC 13 16 27.09 +17 42 00.9     9.96     ~ 594 0
9 NGC 5139 GlC 13 26 47.28 -47 28 46.1           ~ 3299 0
10 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2406 0
11 NGC 5897 GlC 15 17 24.40 -21 00 36.4   10.16 8.52     ~ 370 0
12 M 5 GlC 15 18 33.22 +02 04 51.7     5.95     ~ 1906 0
13 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1784 0
14 M 12 GlC 16 47 14.18 -01 56 54.7     6.07     ~ 635 0
15 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 2027 0
16 NGC 6397 GlC 17 40 42.09 -53 40 27.6     5.17     ~ 1911 0
17 M 22 GlC 18 36 23.94 -23 54 17.1           ~ 1320 0
18 M 54 GlC 18 55 03.33 -30 28 47.5           ~ 1018 0
19 NGC 6752 GlC 19 10 52.11 -59 59 04.4           ~ 1927 0
20 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 821 0
21 M 71 GlC 19 53 46.49 +18 46 45.1           ~ 1085 0
22 M 30 GlC 21 40 22.12 -23 10 47.5     7.10     ~ 998 0
23 NAME Gaia Enceladus-Sausage St* ~ ~           ~ 352 0

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2023.01.27-18:35:06

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