Daniel Pfenniger

Estimating the
actual stellar diffusion in a barred spiral

Maura Brunetti, Cristina Chiappini

We characterize empirically the radial diffusion of stars in a typical
barred disk galaxy by calculating the local spatial diffusion coefficient and
diffusion time-scale for bulge-disk-halo N-body self-consistent systems which
differ initially on the Safronov-Toomre-Q parameter. We find that different
diffusion scenarios appear depending on the bar strength and on the degree of
stability of the disk. Marginally stable disks, with Q~1, have two families of
bar orbits with different values of angular momentum and energy, which
determine a large diffusion in the corotation region. In hot disks (Q>1)
stellar diffusion is reduced with respect to the case of marginally stable
disks. For all models the spatial diffusion is not constant in time and depends
on the activity of the bar, which can move stars all over the disk recurrently.
To realistically study the impact of radial migration on chemical evolution
modeling of the Milky Way, the role of its bar has to be taken into account.