SIMBAD references

Through a detailed analysis of high resolution, high signal to noise spectra, the lithium abundance of sixteen metal deficient binaries (-2.9≤[Fe/H]≤-0.4) with periods ranging from 220d to 1.8d has been measured. All these stars were supposed to be dwarfs. A careful determination of the atmospheric parameters revealed that some of them were slightly evolved. However all the stars here studied (but one: HD 89499) are in the interval 4900≥T_eff≤6200K, logg≥3. The stars are divided in two groups: old disk stars (-1.1≤[Fe/H]≤-0.4) and halo stars ([Fe/H]≤-1.4). The present analysis which includes for most of the stars a careful determination of the stellar physical parameters (T_eff , logg, and [Fe/H]) shows that for T_eff ≥ about 5000K the lithium abundance in long and short period binaries does not differ from that of single dwarfs in the same interval of temperature, gravity and metallicity. When T_eff is ≤ about 5100K the lithium abundance is larger in the short period binaries (which often have larger values of v sini ). Due to the very small number of metal deficient short period binaries, the limit in temperature is rather uncertain and moreover it may depend on the metallicity of the stars. These results, if confirmed by a larger sample would cast some doubts on theories predicting a strong Li depletion in old warm stars (and in particular in Pop II dwarfs) induced by strong angular momentum losses.