The role of radial migration on tracing lithium evolution in the Galactic disc

Abstract

ABSTRACTWith the calculated guiding centre radius Rguiding and birth radius Rbirth, we investigate the role of radial migration on the description of lithium evolution in the Galactic disc based on the upper envelope of the A(Li) versus [Fe/H] diagram. Using migration distances, we find that stars in the solar neighbourhood are born at different locations in the Galactic disc, and cannot all be explained by models of chemical evolution in the solar neighbourhood. It is found that the upper envelope of the A(Li) versus [Fe/H] diagram varies significantly with Rbirth, which explains the decrease of Li for super-metal-rich (SMR) stars because they are non-young stars born in the inner disc. The upper envelope of Li-Rbirth plane fits very well with chemical evolution models by Grisoni et al. for Rbirth = 7–12 kpc, outside which young stars generally lack sufficient time to migrate to the solar neighbourhood. For stars born in the solar neighbourhood, the young open clusters and the upper envelope of field stars with age <3 Gyr fit well with theoretical prediction. We find that calculations using stars with ages less than 3 Gyr are necessary to obtain an undepleted Li upper envelope, and that stars with solar age (around 4.5 Gyr) have depleted around 0.3 dex from the original value based on the chemical evolution model of Grisoni et al.