The effect of stellar migration on Galactic chemical evolution: an heuristic approach

Stellar migration in Galactic disks has been the subject of several investigations in the past years. However, its impact on the chemical evolution of the Milky Way still needs to be fully quantified. In this paper, we aim to impose some constraints on the significance of this phenomenon by considering its influence on the chemical evolution of the Milky Way thin disk. We do not investigate the physical mechanisms underlying the migration of stars. Rather, we introduce a simple, heuristic treatment of stellar migration in a detailed chemical evolution model for the thin disk of the Milky Way, which already includes radial gas flows and reproduces several observational constraints for the solar vicinity and the whole Galactic disk. When stellar migration is implemented according to the results of chemo-dynamical simulations by Minchev et al. and finite stellar velocities of 1 km s−1 are taken into account, the high-metallicity tail of the metallicity distribution function of long-lived, thin-disk stars is well reproduced. By exploring the velocity space, we find that the migrating stars must travel with velocities in the range of 0.5–2 km s−1 to properly reproduce the high-metallicity tail of the metallicity distribution. We confirm previous findings by other authors that the observed spread in the age–metallicity relation of solar neighborhood stars can be explained by the presence of stars that originated at different Galactocentric distances, and we conclude that the chemical properties of stars currently observed in the solar vicinity do suggest that stellar migration is present to some extent.