Evidence for a vanishing 6Li/7Li isotopic signature in the metal-poor halo star HD84937
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Evidence for a vanishing 6Li/7Li isotopic signature in the metal-poor halo star HD84937. / Lind, K.; Asplund, M.; Collet, Remo; Meléndez, J.
I: Memorie della Società Astronomica Italiana. Supplementi, Bind 22, 2012, s. 142-151.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Evidence for a vanishing 6Li/7Li isotopic signature in the metal-poor halo star HD84937
AU - Lind, K.
AU - Asplund, M.
AU - Collet, Remo
AU - Meléndez, J.
PY - 2012
Y1 - 2012
N2 - The claimed detections of 6Li in the atmospheres of some metal-poor halo stars have lead to speculative additions to the standard model of Big Bang nucleosynthesis and the early Universe, as the inferred abundances cannot be explained by Galactic cosmic ray production. A prominent example of a so far un-disputed 6Li-detection is that of the metalpoor turn-off star HD84937, for which at least three different groups obtain very similar results. We revisit the lithium isotopic analysis for this star and two other halo stars, G64-12 and HD140283, using spectra of superiour quality and applying for the first time a combined 3D, NLTE synthesis to both the Li line and to Ca lines that are used to constrain the external line broadening. We demonstrate how differential NLTE effects between the Li and Ca line profiles can lead to spurious 6Li-detections in LTE, compatible with previously reported values of 6Li=7Li ≈ 5%. With our new analysis technique, none of the three analysed stars have a significant detection of 6Li in NLTE.We discuss which further progress is needed to firmly establish these results.
AB - The claimed detections of 6Li in the atmospheres of some metal-poor halo stars have lead to speculative additions to the standard model of Big Bang nucleosynthesis and the early Universe, as the inferred abundances cannot be explained by Galactic cosmic ray production. A prominent example of a so far un-disputed 6Li-detection is that of the metalpoor turn-off star HD84937, for which at least three different groups obtain very similar results. We revisit the lithium isotopic analysis for this star and two other halo stars, G64-12 and HD140283, using spectra of superiour quality and applying for the first time a combined 3D, NLTE synthesis to both the Li line and to Ca lines that are used to constrain the external line broadening. We demonstrate how differential NLTE effects between the Li and Ca line profiles can lead to spurious 6Li-detections in LTE, compatible with previously reported values of 6Li=7Li ≈ 5%. With our new analysis technique, none of the three analysed stars have a significant detection of 6Li in NLTE.We discuss which further progress is needed to firmly establish these results.
KW - G64-12
KW - HD140283
KW - Hydrodynamics
KW - Line: profiles
KW - Radiative transfer
KW - Stars: individual: (HD 84937
KW - Stars: population II
UR - http://www.scopus.com/inward/record.url?scp=84876975862&partnerID=8YFLogxK
M3 - Journal article
AN - SCOPUS:84876975862
VL - 22
SP - 142
EP - 151
JO - Memorie della Società Astronomica Italiana. Supplementi
JF - Memorie della Società Astronomica Italiana. Supplementi
SN - 1824-0178
Y2 - 27 February 2012 through 29 February 2012
ER -
ID: 183472030