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Using the sample of 348 stars from the PennState-Torun Centre for AstronomyPlanet Search, for which uniformly determined atmospheric parameters areavailable, with chemical abundances and rotational velocities presented here,we investigate various channels of Li enrichment in giants. Our work is basedon the HET/HRS spectra. The A(Li) was determined from the 670.8nm line, whilewe use a more extended set of lines for alpha-elements abundances. In a seriesof K-S tests, we compare Li-rich giants with other stars in the sample. We alsouse available IR photometric and kinematical data in search for evidence ofmass-loss. We investigate properties of the most Li-abundant giants in moredetail by using multi-epoch precise radial velocities. We present Li andalpha-elements abundances, as well as vsini for 348 stars. We detected Li in 92stars, of which 82 are giants. 11 of them show significant Li abundanceA(Li)>1.4 and 7 of them are Li-overabundant objects, according to criterion ofA(Li)>1.5 and their location on HR diagram, including two giants with Liabundances close to meteoritic level. For another 271 stars, upper limits ofA(Li) are presented. We show that Li-rich giants are among the most massivestars from our sample and show larger than average effective temperatures. Theyare indistinguishable from the complete sample in terms of their distributionof luminosity, [Fe/H], vsini, and alpha-elements abundances. Our results do notpoint out to one specific Li enrichment mechanism operating in our sample ofgiants. On the contrary, in some cases, we cannot identify fingerprints of anyof known scenarios. We show, however, that the 4 most Li-rich giant in oursample either have low-mass companions or have RV variations at the level of~100 m/s, which strongly suggests that the presence of companions is animportant factor in the Li-enrichment processes in giants.

The Penn State - Torun Centre for Astronomy Planet Search stars. II. Lithium abundance analysis of the Red Giant Clump sample