Astron. Astrophys. 337, 739-753 (1998)

The age-mass relation for chromospherically active binaries

III. Lithium depletion in giant components ^*

D. , Barrado , y , Navascués ^{1, 2}, E. , De , Castro ³, M.J. , Fernández-Figueroa ³, M. , Cornide ³, R.J. , García and López <sup>4

1</sup> MEC/Fulbright Fellow at the Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA 02138, USA
² Real Colegio Complutense at Harvard University, Trowbridge St, Cambridge, MA 02138, USA
³ Departamento de Astrofísica, Facultad de Físicas, Universidad Complutense, E-28040 Madrid, Spain
⁴ Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain

Received 4 March 1998 / Accepted 12 June 1998

Abstract

We present a study of the lithium abundances of a sample of evolved components of Chromospherically Active Binary Systems. We show that a significant part of them have lithium excesses, independently of their mass and evolutionary stage. Therefore, it can be concluded that Li abundance does not depend on age for giant components of CABS. These overabundances appear to be closely related to the stellar rotation, and we interpret them as a consequence of the transfer of angular momentum from the orbit to the rotation as the stars evolve in and off the Main Sequence, in a similar way as it happens in the dwarf components of the same systems and in the Tidally Locked Binaries belonging to the Hyades and M67.

Key words: stars: abundances stars: activity stars: evolution stars: late-type stars: rotation

* Based on observations collected with the 2.2 m telescope of the German-Spanish Observatorio de Calar Alto (Almería, Spain), and with the 2.56 m Nordic Optical Telescope in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (La Palma, Spain)

Send offprint requests to: D. Barrado y Navascués (e-mail: dbarrado@cfa.harvard.edu)

SIMBAD Objects

Contents

• 1. Introduction
• 2. Program stars and observations
• 3. Temperatures, lithium abundances, masses and ages
  • 3.1. Effective temperature
  • 3.2. Lithium abundance
  • 3.3. Masses and ages
• 4. The dependence of lithium on several stellar parameters
  • 4.1. Li abundance vs. effective temperature
  • 4.2. The mass-log N(Li) plane
  • 4.3. Lithium and age
  • 4.4. Lithium and rotation
• 5. Summary and conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: August 27, 1998
helpdesk.link@springer.de