The lithium content of the globular cluster NGC 6397

By P. Bonifacio, L. Pasquini, F. Spite, A. Bragaglia, E. Carretta, V. Castellani, M. Centurión, A. Chieffi, R. Claudi, Gisella Clementini and 20 more. 2002

143 citations recorded by the source corpus.

We make use of high resolution, high signal-to-noise ratio spectra of 12 turn-o stars in the metal-poor globular cluster NGC 6397 to measure its lithium content. We conclude that they all have the same lithium abundance A(Li)= 2:34 with a standard deviation of 0.056 dex. We use this result, together with Monte Carlo simulations, to estimate that the maximum allowed intrinsic scatter is of the order of 0.035 dex. This is a new stringent constraint to be fulfilled by stellar models which predict Li depletion. We argue that although a mild depletion of 0.1-0.2 dex, as predicted by recent models, cannot be ruled out, there is no compelling reason for it. This fact, together with the good agreement with the Li abundance observed in field stars, supports the primordial origin of lithium in metal-poor stars. Taking the above value as the primordial lithium abundance implies a cosmic baryonic density which is eitherbh 2 = 0:016 0:004 orbh 2 = 0:005 +0:0026 0:0006 , from the predictions of standard big bang nucleosynthesis. The high baryonic density solution is in agreement with recent results on the primordial abundance of deuterium and 3 He and on the estimates derived from the fluctuations of the cosmic microwave background.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/0b8e2e7db8591c97619c35861fa9b80ddf27bf3b

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

Multiple populations in globular clusters (2012, background): “(2007): the globular clusters must have been initially a large factor (10-100) more massive than today and almost all the first generation stars must have been preferentially lost.”
Abundance Variations within Globular Clusters (2004, result): “In the case of NGC6397 (Castilho et al. 2000, Bonifacio et al. 2002) and M92 (Bonifacio 2002), the average Li abundance in TO stars is not much different from that observed for stars on the Spite’s plateau, with a scatter around this value consistent with observational errors alone (see, however,…”
A Large Stellar Evolution Database for Population Synthesis Studies. I. Scaled Solar Models and Isochrones (2004, background): “…efficient, spectroscopic observations of, for example, stars in Galactic globular clusters or field halo stars (see, e.g., Gratton et al. 2001; Bonifacio et al. 2002 and references therein) point to a drastically reduced efficiency of diffusion that may be due to the counteracting effect of…”
First stars XII. Abundances in extremely metal-poor turnoff stars,and comparison with the giants (2009, background): “As we pointed out in Paper VII, the adoption of a higher effective temperature for the turn-off stars of this cluster, as done by Bonifacio et al. (2002), would largely cancel the abundance differences between TO and RGB.”
Full computation of massive AGB evolution. I. The large impact of convection on nucleosynthesis (2004, result): “Lithium: The constant lithium content of the ejecta, independent of the convective model, is in good agreement with the observed lithium abundances of NGC 6397 TO stars (Bonifacio et al. 2002), which all show approximately the same population II standard value.”
A Realistic Determination of the Error on the Primordial Helium Abundance: Steps toward Nonparametric Nebular Helium Abundances (2004, background): “Even a recent study (Bonifacio et al. 2002) with temperatures based on H lines observed in the atmospheres of halo dwarf stars (considered to give systematically high temperatures) yields 7Li=H ¼ (2:19 0:28) ; 10 10.”
Updated Big Bang nucleosynthesis confronted to WMAP observations and to the abundance of light elements (2003, methodology): “The data of Thévenin et al. (2001) and Bonifacio et al. (2002) are also included.”
Atomic Diffusion and Mixing in Old Stars. I. Very Large Telescope FLAMES-UVES Observations of Stars in NGC 6397 (2007, methodology): “Bonifacio et al. (2002) derive lithium abundances for 12 TOP in NGC 6397 drawn from the studies of G01 and Thévenin et al. (2001).”
First stars VII - Lithium in extremely metal poor dwarfs (2006, methodology): “The highest values claimed for the Spite plateau (Bonifacio et al. 2002; Meléndez & Ramírez 2004) are about 0.3 dex lower; many other recent claims are lower still.”
Implications of WMAP Observations on Li Abundance and Stellar Evolution Models (2004, methodology): “In particular Spite et al. (1984), Ryan et al. (1999), Bonifacio et al. (2002), Thorburn (1994) and Bonifacio (2002) have confirmed a plateau at1 A(Li) ≃ 2.1 or at A(Li) ≃ 2.3 depending on the Teff scale used.”
Signatures of intrinsic Li depletion and Li-Na anti-correlation in the metal-poor globular cluster NGC 6397 , (2009, methodology): “In previous analyses, Bonifacio et al. (2002) analyse Li in twelve TO stars (of which seven stars were previously analysed by Thévenin et al. 2001 and three stars by Pasquini & Molaro 1996) and Korn et al. (2007) analyse five TO stars and two SGB stars.”
Abundances of C, N, O in slightly evolved stars in the globular clusters NGC 6397, NGC 6752 and 47 Tuc (2004, result): “We would then expect that Li be depleted by a factor of 2 to 5 in main sequence stars of globular clusters like NGC 6397, in contrast with observations (Bonifacio et al. 2002).”