J/A+A/618/A134 Omega Cen lower red giant stars abundances (Mucciarelli+, 2018)
Lithium abundance in lower red giant branch stars of Omega Centauri.
Mucciarelli A., Salaris M., Monaco L., Bonifacio P., Fu X., Villanova S.
<Astron. Astrophys. 618, A134 (2018)>
=2018A&A...618A.134M 2018A&A...618A.134M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, population II ; Abundances
Keywords: stars: abundances - stars: evolution - stars: Population II -
globular clusters: individual: Omega Centauri - stars: evolution
Abstract:
We present Li, Na, Al and Fe abundances of 199 lower red giant branch
stars members of the stellar system Omega Centauri, using
high-resolution spectra acquired with FLAMES at the Very Large
Telescope. The A(Li) distribution is peaked at A(Li)∼1dex with a
prominent tail toward lower values. The peak of the distribution well
agrees with the lithium abundances measured in lower red giant branch
stars in globular clusters and Galactic field stars. Stars with
A(Li)∼1dex are found at metallicities lower than [Fe/H]~-1.3dex but
they disappear at higher metallicities. On the other hand, Li-poor
stars are found at all the metallicities. The most metal-poor stars
exhibit a clear Li-Na anticorrelation, with about 30% of the sample
with A(Li) lower than ∼0.8dex, while in normal globular clusters these
stars represent a small fraction. Most of the stars with
[Fe/H]>-1.6dex are Li-poor and Na-rich. The Li depletion measured in
these stars is not observed in globular clusters with similar
metallicities and we demonstrate that it is not caused by the proposed
helium enhancements and/or young ages. Hence, these stars formed from
a gas already depleted in lithium. Finally, we note that Omega
Centauri includes all the populations (Li-normal/Na-normal,
Li-normal/Na-rich and Li-poor/Na-rich stars) observed, to a lesser
extent, in mono-metallic GCs.
Description:
Main information (identification number, coordinates, magnitudes,
radial velocities) of the observed targets and the corresponding
chemical abundances of Fe, Li, Na and Al.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 199 Main information on the observed FLAMES targets
table2.dat 94 199 Relative abundances of the FLAMES targets
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See also:
J/A+A/493/959 : UBV(RI)cHalpha photometry in omega Cen (Bellini+, 2009)
J/AJ/135/1395 : omega Cen Spitzer photometry (Boyer+, 2008)
J/A+A/360/472 : Proper motions in omega Centauri (van Leeuwen+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID Star identification number (1)
10- 19 F10.6 deg RAdeg Right ascension (J2000)
23- 32 F10.6 deg DEdeg Declination (J2000)
36- 41 F6.3 mag Bmag Johnson B magnitude
45- 50 F6.3 mag Vmag Johnson V magnitude
54- 59 F6.3 mag Imag Cousins I magnitude
63- 68 F6.3 mag Ksmag ?=0 2MASS Ks magnitude
72- 76 F5.1 km/s RV Radial velocity
80- 82 F3.1 km/s e_RV Uncertainty on RV
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Note (1): From Bellini et al., 2009, Cat. J/A+A/493/959. Will be
Cl* NGC 5139 BPB NNNNNN in Simbad.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID Star identification number
10- 13 I4 K Teff Effective temperature
17- 20 F4.2 [cm/s2] logg Surface gravity
24- 26 F3.1 km/s Vt Microturbulent velocity
30- 34 F5.2 [Sun] [Fe/H] Relative abundance [Fe/H]
38- 41 F4.2 [Sun] e_[Fe/H] Uncertainty on [Fe/H]
46- 49 F4.2 [-] A(Li) Absolute abundance A(Li)
53- 56 F4.2 [-] e_A(Li) ?=0 Uncertainty on A(Li)
60 I1 --- l_A(Li) [0/1] Limit flag on A(Li), 1 if upper limit
64- 68 F5.2 [Sun] [Na/Fe] Relative abundance [Na/Fe]
72- 75 F4.2 [Sun] e_[Na/Fe] Uncertainty on [Na/Fe]
79- 83 F5.2 [Sun] [Al/Fe] Relative abundance [Al/Fe]
87- 90 F4.2 [Sun] e_[Al/Fe] ?=0 Uncertainty on [Al/Fe]
94 I1 --- l_[Al/Fe] [0/1] Limit flag on [Al/Fe], 1 if upper limit
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Acknowledgements:
Alessio Mucciarelli, alessio.mucciarelli2(at)unibo.it
(End) Patricia Vannier [CDS] 27-Jul-2018