The lithium-rotation connection in the Psc-Eri stream

The evolution of lithium abundance over a stellar lifetime is indicative of transport processes operating in stellar interiors. These non-standard transport processes could be affected by structural changes induced by rotation, magnetic activity, metallicity, or accretion. In this work, we study the connection between lithium content and rotation in low-mass stars belonging to the recently discovered Psc--Eri stellar stream, which has an age similar to the Pleiades (125~Myr). We obtained the rotational periods from the literature and complemented this data with optical spectra for 40 candidate members of the Psc--Eri stream. The spectra were obtained with the FEROS high-resolution spectrograph at the ESO/MPG 2.2m telescope at La Silla Observatory. To estimate the lithium content, we measured the equivalent width of the 607.8 nm Li I line. We found that a clear relation exists between the lithium content and rotation rate for a restricted range of spectral types (from late-G to early-K), where slow rotators are more lithium depleted compared with faster rotators at similar temperatures. This connection is notably similar to that previously reported for the Pleiades cluster. The two main implications of this results are: 1) the lithium--rotation relation seems to be universal for low-mass stars close to the zero-age main sequence over a specific effective temperature range; and 2) given the probably different initial conditions and evolution of the Psc--Eri stellar stream respect to that of the Pleiades, it seems that the lithium--rotation connection does not depend on environmental effects.