Volume 428, Number 2, December III 2004
|Page(s)||579 - 586|
|Published online||26 November 2004|
A low upper-limit on the lithium isotope ratio in HD140283*
National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan e-mail: firstname.lastname@example.org;email@example.com;firstname.lastname@example.org
2 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany e-mail: email@example.com
3 Max-Planck-Institut für Kernphysik, Postfach 103980, 69029 Heidelberg, Germany
4 Centre for Earth, Planetary, Space and Astronomical Research, Dept of Physics & Astronomy, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK e-mail: firstname.lastname@example.org
5 Department of Astronomy, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
6 Department of Physics, Kyoto University, Kitashirakawa, Kyoto 606-8502, Japan
7 Liberal Arts Education Center, Tokai University, 1117 Kitakaname, Hiratsuka-shi, Kanagawa, 259-1292, Japan e-mail: email@example.com,jp
Accepted: 28 August 2004
We have obtained a high- (900–1100), high-resolving-power () spectrum of the metal-poor subgiant HD 140283 in an effort to measure its 6Li/7Li isotope ratio. From a 1-D atmospheric analysis, we find a value consistent with zero, 6Li/7Li = 0.001, with an upper limit of 6Li/7Li < 0.018. This measurement supersedes an earlier detection (0.040 ± 0.015()) by one of the authors. HD 140283 provides no support for the suggestion that Population II stars may preserve their 6Li on the portion of the subgiant branch where 7Li is preserved. However, this star does not defeat the suggestion either; being at the cool end of the subgiant branch of the Spite plateau, it may be sufficiently cool that 6Li depletion has already set in, or the star may be sufficiently metal poor that little Galactic production of 6Li had occurred. Continued investigation of other subgiants is necessary to test the idea. We also consider the implications of the HD 140283 upper limit in conjunction with other measurements for models of 6Li production by cosmic rays from supernovae and structure formation shocks.
Key words: stars: abundances / stars: Population II / Galaxy: halo / Galaxy: kinematics and dynamics / Galaxy: structure / nuclear reactions, nucleosynthesis, abundances
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.