J/MNRAS/449/4038 Li abundance of giants in 3 globular clusters (D'Orazi+, 2015) ================================================================================ Lithium abundances in globular cluster giants: NGC 1904, NGC 2808, and NGC 362. D'Orazi V., Gratton R.G., Angelou G.C., Bragaglia A., Carretta E., Lattanzio J.C., Lucatello S., Momany Y., Sollima A., Beccari G. =2015MNRAS.449.4038D ================================================================================ ADC_Keywords: Clusters, globular ; Stars, population II ; Abundances Keywords: stars: abundances - stars: Population II - globular clusters: individual: NGC 1904 - globular clusters: individual: NGC 2808 - globular clusters: individual: NGC 362 Abstract: The presence of multiple populations in globular clusters has been well established thanks to high-resolution spectroscopy. It is widely accepted that distinct populations are a consequence of different stellar generations: intra-cluster pollution episodes are required to produce the peculiar chemistry observed in almost all clusters. Unfortunately, the progenitors responsible have left an ambiguous signature and their nature remains unresolved. To constrain the candidate polluters, we have measured lithium and aluminium abundances in more than 180 giants across three systems: NGC 1904, NGC 2808, and NGC 362. The present investigation along with our previous analysis of M12 and M5 affords us the largest database of simultaneous determinations of Li and Al abundances. Our results indicate that Li production has occurred in each of the three clusters. In NGC 362 we detected an M12-like behaviour, with first and second-generation stars sharing very similar Li abundances favouring a progenitor that is able to produce Li, such as AGB stars. Multiple progenitor types are possible in NGC 1904 and NGC 2808, as they possess both an intermediate population comparable in lithium to the first generation stars and also an extreme population, that is enriched in Al but depleted in Li. A simple dilution model fails in reproducing this complex pattern. Finally, the internal Li variation seems to suggest that the production efficiency of this element is a function of the cluster's mass and metallicity - low-mass or relatively metal-rich clusters are more adept at producing Li. Description: Observations were carried out in visitor mode with FLAMES mounted at UT2 of ESO-VLT on 2014 December 11-13 (Program 094.D-0363(A)). Spectra were collected with the scientific aim of inferring Li and Al abundances for large samples of RGB stars, below and above the RGB bump luminosity, in several GCs, as part of our dedicated survey (see Paper I, D'Orazi et al., 2014ApJ...791...39D). File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 100 185 Photometry, stellar parameters, kinematics, and chemical information for our sample stars -------------------------------------------------------------------------------- See also: J/A+A/548/A92 : VrI light curves of NGC1904 variables (Kains+, 2012) J/MNRAS/437/1609 : NGC 2808 HB stars abundances (Marino+, 2014) J/MNRAS/437/1609 : NGC 2808 HB stars abundances (Marino+, 2014) J/A+A/557/A138 : Detailed chemical abundances in NGC 362 (Carretta+ 2013) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 I4 --- NGC NGC number of globular cluster (1) 5 A1 --- --- [-] 6- 10 I5 --- ID Star identification in cluster (1) 12- 13 I2 h RAh Right ascension J2000, Epoch 2000 15- 16 I2 min RAm Right Ascension J2000 18- 22 F5.2 s RAs Right Ascension J2000 24 A1 --- DE- Declination sign J2000 25- 26 I2 deg DEd Declination J2000, Epoch 2000 28- 29 I2 arcmin DEm Declination J2000 31- 34 F4.1 arcsec DEs Declination J2000 36- 41 F6.3 mag Bmag B magnitude 43- 48 F6.3 mag Vmag V magnitude 50- 55 F6.3 mag Ksmag ? 2MASS Ks magnitude 57- 62 F6.2 km/s RV [83/239] Heliocentric radial velocity 64- 66 I3 --- S/N [90/211] Signal-to-noise ratio at 6708{AA} 68- 71 I4 K Teff [4425/5183] Effective temperature 73- 76 F4.2 cm/s2 logg [1.1/2.9] Surface gravity 78- 81 F4.2 km/s xi [1.9/1.9] Microturbulence velocity {xi} 83 A1 --- l_A(Li)e [<] Upper limit on Li abundance 84- 87 F4.2 [-] A(Li)e [0/1.13]? LTE Li abundance 89 A1 --- l_A(Li)n [<] Upper limit on Li abundance 90- 93 F4.2 [-] A(Li)n [0/1.21]? non-LTE Li abundance 95 A1 --- l_[Al/Fe] [<] Upper limit on Al/Fe 96-100 F5.2 [Sun] [Al/Fe] [-0.3/0.98]? Aluminium abundances -------------------------------------------------------------------------------- Note (1): Star identification as NNNN-NNNNN where the first number is the NGC number, and the second number the Star number. -------------------------------------------------------------------------------- Acknowledgements: Valentina D'Orazi, valentina.dorazi(at)oapd.inaf.it ================================================================================ (End) Patricia Vannier [CDS] 17-Apr-2015