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Astron. Astrophys. 357, L49-L52 (2000)


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Letter to the Editor

The lithium isotope ratio in the metal-poor halo star G271-162 from VLT/UVES observations *

P.E. Nissen 1, M. Asplund 2, V. Hill 3 and S. D'Odorico 3

1 University of Aarhus, Institute of Physics and Astronomy, 8000 Aarhus C, Denmark (pen@ifa.au.dk)
2 Uppsala Astronomical Observatory, Box 515, 751 20, Sweden (martin@astro.uu.se)
3 European Southern Observatory, Karl-Schwarzschild Strasse 2, 85748 Garching b. München, Germany (vhill@eso.org, sdodoric@eso.org)

Received 16 March 2000 / Accepted 11 April 2000

Abstract

A high resolution ([FORMULA]), very high [FORMULA] ([FORMULA]) spectrum of the metal-poor turnoff star G 271-162 has been obtained in connection with the commissioning of UVES at VLT/Kueyen. Using both 1D hydrostatic and 3D hydrodynamical model atmospheres, the lithium isotope ratio has been estimated from the [FORMULA] 670.8 nm line by means of spectral synthesis. The necessary stellar line broadening (1D: macroturbulence + rotation, 3D: rotation) has been determined from unblended KI , CaI and FeI lines. The 3D line profiles agree very well with the observed profiles, including the characteristic line asymmetries. Both the 1D and 3D analyses reveal a possible detection of [FORMULA] in G 271-162, [FORMULA] ([FORMULA]). It is discussed if the smaller amount of [FORMULA] in G 271-162 than in the similar halo star HD 84937 could be due to differences in stellar mass and/or metallicity or whether it may reflect an intrinsic scatter of [FORMULA] in the ISM at a given metallicity.

Key words: stars: abundances – stars: atmospheres – stars: fundamental parameters – stars: individual: G271-162 – ISM: cosmic rays

* Based on public data released from the UVES commissioning at the VLT/Kueyen telescope, ESO, Paranal, Chile

Send offprint requests to: P.E. Nissen

© European Southern Observatory (ESO) 2000

Online publication: June 5, 2000

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