2001A&A...376..955S


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.17CET14:58:47

2001A&A...376..955S - Astronomy and Astrophysics, volume 376, 955-965 (2001/9-4)

Atomic diffusion in metal-poor stars. II. Predictions for the Spite plateau.

SALARIS M. and WEISS A.

Abstract (from CDS):

We have computed a grid of up-to-date stellar evolutionary models including atomic diffusion, in order to study the evolution with time of the surface Li abundance in low-mass metal-poor stars. We discuss in detail the dependence of the surface Li evolution on the initial metallicity and stellar mass, and compare the abundances obtained from our models with the available Li measurements in Pop II stars. While it is widely accepted that the existence of the Spite Li-plateau for these stars is a strong evidence that diffusion is inhibited, we show that, when taking into account observational errors, uncertainties in the Li abundance determinations, in the Teff scale, and in particular the size of the observed samples of stars, the Spite plateau and the Li abundances in subgiant branch stars can be reproduced also by models including fully efficient diffusion, provided that the most metal-poor field halo objects are between 13.5 and 14Gyr old. We provide the value of the minimum number of plateau stars to observe, for discriminating between efficient or inhibited diffusion. From our models with diffusion we derive that the average Li abundance along the Spite plateau is about a factor of 2 lower than the primordial one. As a consequence, the derived primordial Li abundance would be consistent with a high helium and low deuterium Big Bang Nucleosynthesis; this implies a high cosmological baryon density as inferred from the analyses of the cosmic microwave background.

Abstract Copyright:

Journal keyword(s): stars: Population II - evolution - abundances - physical data and processes: diffusion

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3472 0
2 HD 84937 PM* 09 48 56.09801 +13 44 39.3237 8.49 8.68 8.32 7.97 7.70 F8Vm-5 708 0
3 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 845 0
4 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 1870 0
5 NGC 6397 GlC 17 40 42.09 -53 40 27.6   7.39 5.17     ~ 1756 1
6 NGC 6752 GlC 19 10 52.11 -59 59 04.4   6.96 6.28     ~ 1766 0
7 HD 218502 PM* 23 08 39.3725624892 -15 03 11.944865393   8.65 8.25     F(3)w 86 0

    Equat.    Gal    SGal    Ecl

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2019.11.17-14:58:47

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