Migration and azimuthal variations (P. Di Matteo et al.)

Vol. 553
In section 5. Galactic Structure, stellar clusters and population

Signatures of radial migration in barred galaxies: Azimuthal variations in the metallicity distribution of old stars

The authors used N-body simulations to show that radial migration of stars in a galaxy disk, which are induced by a bar and spiral arms, can lead to significant azimuthal variation in the metallicity distribution of old stars at various distances from the center of a galaxy. These variations are predicted to be most visible when the bar is strongest, and they will diminish as the bar fades. Once the migration finishes up, then the mixing processes will start to smooth the disk out once again. These simulations thus suggest that the presence of inhomogeneities in the metallicity distribution of older stars in the disk of a barred galaxy can be used to as a probe of ongoing stellar migration within the disk. These signatures may be observable in the Milky Way by GAIA and related spectroscopic surveys. They should also be visible in external galaxies in the detailed IFU observations of stellar disks.