2009A&A...504..213G


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.14CET09:25:25

2009A&A...504..213G - Astronomy and Astrophysics, volume 504, 213-223 (2009/9-2)

6Li/7Li estimates for metal-poor stars.

GARCIA PEREZ A.E., AOKI W., INOUE S., RYAN S.G., SUZUKI T.K. and CHIBA M.

Abstract (from CDS):

The presence of the lithium-6 isotope in some metal-poor stars is a matter of surprise because of the high values observed. Non-standard models of Big Bang nucleosynthesis and pre-Galactic cosmic ray fusion and spallation have been proposed to explain these values. However, the observations of this light isotope are challenging which may make some detections disputable. The goal was to determine 6Li/7Li for a sample of metal-poor stars; three of them have been previously studied and the remaining two are new for this type of study. The purpose was to increase, if possible, the number of lithium-6 detections and to confirm previously published results. Spectra of the resonance doublet line of neutral lithium LiI 670.78nm were taken with the high dispersion spectrograph at the Subaru 8.2m-telescope for a sample of five metal-poor stars (-3.12≤[Fe/H]≤-2.19). The contribution of lithium-6 to the total observed line profile was estimated from the 1D-LTE analysis of the line asymmetry.Observed asymmetries could be reproduced assuming isotopic abundance ratios 6Li/7Li of the order of: 0.004 for BD +26 3578, ∼0.010 for BD +02 3375 and G 64-37, 0.025 for BD +20 3603 and 0.047 for BD -04 3208. We found that these results were very sensitive to several of the assumptions made in the analysis, in particular, the treatment of the residual structure in the analysed spectra. Our final estimates for the errors are respectively Δ6Li/7Li=±0.028, 0.029, 0.039, 0.025 and 0.039. The 6Li/7Li ratios for the sample are comparable to or even lower than these error values, so that detections of lithium-6 can not safely be claimed despite of the high resolving power (R∼95000) and S/N (400-600).

Abstract Copyright:

Journal keyword(s): line: profiles - stars: abundances - stars: atmospheres - stars: population II - Galaxy: evolution

Simbad objects: 12

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Number of rows : 12

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 BD-10 388 PM* 01 50 32.6463515122 -09 21 02.838270707   10.78 10.37     F3 83 0
2 HD 74000 PM* 08 40 50.8038415228 -16 20 42.513275817 9.84 10.09 9.66     F2 242 0
3 HD 84937 PM* 09 48 56.09801 +13 44 39.3237 8.49 8.68 8.32 7.97 7.70 F8Vm-5 711 0
4 BD+02 2375 * 11 00 37.1331821167 +02 01 25.217003695   10.97 10.39     F0 2 0
5 BD-04 3208 PM* 12 07 15.0719832426 -05 44 01.609304815   10.40 9.99     A7 131 0
6 Ross 841 PM* 14 02 30.0901582051 -05 39 05.181328144   11.508 11.149 10.866 10.576 sdA3 134 0
7 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 847 0
8 BD+42 2667 PM* 16 03 13.2989292029 +42 14 46.649595940   10.33   9.6   F5 130 0
9 BD+02 3375 PM* 17 39 45.5950264172 +02 24 59.607595293 10.18 10.40 9.92 9.47 9.12 A5 180 0
10 BD+20 3603 PM* 17 54 43.2306261669 +20 16 16.443521966   10.13   9.6   F0 145 0
11 HD 338529 PM* 19 32 31.9104538188 +26 23 26.116678290   9.72   9.2   B5 194 0
12 LP 815-43 PM* 20 38 13.2997980664 -20 26 10.852305467   11.31 10.72     ~ 64 0

    Equat.    Gal    SGal    Ecl

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2019.12.14-09:25:25

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