EDP Sciences
Free access
Volume 382, Number 3, February II 2002
Page(s) 1016 - 1020
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20011676

A&A 382, 1016-1020 (2002)
DOI: 10.1051/0004-6361:20011676

The tidal effects on the lithium abundance of binary systems with giant component

J. M. Costa1, L. da Silva2, J. D. do Nascimento Jr.1 and J. R. De Medeiros1

1  Departamento de Física, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, R.N., Brazil
2  Observatório Nacional, Rio de Janeiro, RJ, Brazil

(Received 21 July 2001 / Accepted 22 November 2001 )

We analyse the behavior of lithium abundance as a function of effective temperature, projected rotational velocity, orbital period and eccentricity for a sample of 68 binary systems with giant component and orbital period ranging from about 10 to 6400 days. For these binary systems the Li abundances show a gradual decrease with temperature, paralleling the well established result for single giants. We have also observed a dependence of lithium content on rotation. Binary systems with moderate to high rotation present also moderate to high Li content. This study shows also that synchronized binary systems with giant component seem to retain more of their original lithium than the unsynchronized systems. For orbital periods lower than 100 to 250 days, typically the period of synchronization for this kind of binary systems, lithium depleted stars seems to be unusual. The suggestion is made that there is an "inhibited zone" in which synchronized binary systems with giant component having lithium abundance lower than a threshold level should be unusual.

Key words: stars: binaries -- stars: abundances -- stars: evolution -- stars: interiors -- stars: late-type

Offprint request: J. M. Costa, damata@dfte.ufrn.br

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