2019A&A...628A.111G


Query : 2019A&A...628A.111G

2019A&A...628A.111G - Astronomy and Astrophysics, volume 628A, 111-111 (2019/8-1)

The 6Li/7Li isotopic ratio in the metal-poor binary CS22876-032.

GONZALEZ HERNANDEZ J.I., BONIFACIO P., CAFFAU E., LUDWIG H.-G., STEFFEN M., MONACO L. and CAYREL R.

Abstract (from CDS):


Aims. We present high-resolution and high-quality UVES spectroscopic data of the metal-poor double-lined spectroscopic binary CS 22876-032 ([Fe/H] approximately -3.7dex). Our goal is to derive the 6Li/7Li isotopic ratio by analysing the LiIλ 670.8nm doublet.
Methods. We co-added all 28 useful spectra normalised and corrected for radial velocity to the rest frame of the primary star. We fitted the Li profile with a grid of the 3D non-local thermodynamic equilibrium (NLTE) synthetic spectra to take into account the line profile asymmetries induced by stellar convection, and performed Monte Carlo simulations to evaluate the uncertainty of the fit of the Li line profile. Results. We checked that the veiling factor does not affect the derived isotopic ratio, 6Li/7Li, and only modifies the Li abundance, A(Li), by about 0.15dex. The best fit of the Li profile of the primary star provides A(Li)=2.17±0.01dex and 6Li/7Li=8–5+2% at 68% confidence level.In addition, we improved the Li abundance of the secondary star at A(Li)=1.55±0.04dex, which is about 0.6dex lower than that of the primary star.Conclusions. The analysis of the Li profile of the primary star is consistent with no detection of 6Li and provides an upper limit to the isotopic ratio of 6Li/7Li<10% at this very low metallicity, about 0.5dex lower in metallicity than previous attempts for detection of 6Li in extremely metal poor stars. These results do not solve or worsen the cosmological 7Li problem, nor do they support the need for non-standard 6Li production in the early Universe.

Abstract Copyright: © ESO 2019

Journal keyword(s): stars: Population II - stars: individual: CS22876-032 - Galaxy: abundances - Galaxy: halo - cosmology: observations - primordial nucleosynthesis

VizieR on-line data: <Available at CDS (J/A+A/628/A111): cs22876a.dat cs22876b.dat>

CDS comments: Paragraph.1 SDSS J0135+0641 is a misprint for SDSS J1035+0641.

Simbad objects: 9

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Number of rows : 9
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 SB 44 SB* 00 07 37.5160264968 -35 31 17.704959708   13.23 12.76 12.76   sdF 81 0
2 SDSS J002314.00+030758.0 * 00 23 14.0027073768 +03 07 58.241752572           A2II 22 0
3 BD+44 493 Pe* 02 26 49.7390353632 +44 57 46.523771136   9.63 9.11     CEMP-no 104 0
4 HE 1029-0546 Pe* 10 31 48.1191917592 -06 01 43.943123568   15.987 15.632 15.316   CEMP-s 10 0
5 SDSS J103556.11+064143.9 Pe* 10 35 56.1158830560 +06 41 44.004045912           CEMP-no 26 0
6 HE 1241-2907 Pe* 12 44 12.9747861960 -29 23 48.042681072   16.15 15.59 15.76   CEMP-mp 4 0
7 BD+26 2606 SB* 14 49 02.3593347728 +25 42 09.192358874 9.92 10.16 9.73 9.27 8.95 A5 373 0
8 SDSS J150702.02+005152.6 Pe* 15 07 02.0210528784 +00 51 52.610505084           A0 5 0
9 UCAC4 195-177220 SB* 18 08 20.0315466960 -51 04 37.883300340   12.546 11.930 11.898   CEMP 25 0

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