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. =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: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Note (1): From Bellini et al., 2009, Cat. J/A+A/493/959. Will be Cl* NGC 5139 BPB NNNNNN in Simbad. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Acknowledgements: Alessio Mucciarelli, alessio.mucciarelli2(at)unibo.it ================================================================================ (End) Patricia Vannier [CDS] 27-Jul-2018