PENELLOPE. IX. Lithium, iron, and barium elemental abundances in eight nearby young clusters

We conducted a homogeneous chemical analysis of pre-main sequence stars with effective temperatures ranging from ∼ 3000 K to ∼ 5500 K in eight nearby star-forming regions (SFRs): Chamaeleon I, η Chamaeleonis, Lupus, Orion OB1a, Orion OB1b, σ, Orionis, Taurus, and Corona-Australis. Our study aims to: 1) derive the lithium (Li) abundance (A (Li) ) and highlight the impact of veiling correction on both the A (Li) and age determination; 2) perform an iron (Fe) and barium (Ba) abundance analysis in regions with scarce previous measurements; and 3) investigate the possible Ba enhancement. The analyzed data were obtained as part of the PENELLOPE Large Program using the ESPRESSO, UVES, and X-Shooter instruments. We measured the equivalent width (EW) of the Li line (EW_̊m Li) at łambda = 6707. 8 Å, from which Åm (Li) was derived using the curves of growth method. The Fe and Ba abundances have been measured through spectral synthesis analysis. Using the EAGLES code, we derived an upper limit on the age of the eight SFRs. Our findings underscore the necessity of veiling corrections on EW_̊m Li, which can shift Åm (Li) and age estimates by up to ∼ 0. 7 dex and ∼ 20 Myr, respectively. When accounting for veiling, the A values reaching up to 0. 75 dex. (Li) distributions peak in a range between 3. 3 and 3. 8 dex for most clusters and the upper age limit is approximately 5 Myr for all SFRs. We successfully measured the mean Fe and Ba abundances in Lupus, Taurus, Cha I, and η Cha, finding slightly subsolar Fe abundances and a clear Ba overabundance, with Ba/H