Lithium and binarity

Abstract

We present an analysis of the lithium abundances in late spectral type binaries of different ages. They belong to several open clusters (Pleiades, Hyades and M67), as well as to Chromospherically Active Binary Systems (CABS). All these binaries have reliable ages, since they are members of well-known open clusters or, in the case of the CABS, some stellar parameters such masses and radii are accurate enough to derive ages using theoretical isochrones. Their age span covers from barely one hundred million years to several gigayears. We have compared different stellar properties, such as lithium abundances, stellar masses, effective temperatures and orbital periods. It is shown that, in general, close binaries have lithium abundances larger than those characteristic of single stars or binaries with larger orbital periods. The largest difference between the abundances of binaries and single stars appears at Hyades' age. The origin of those overabundances are discussed in the context of the proposed mechanisms for the lithium depletion phenomenon and the stellar evolution.