Seminari DAM: “The dynamical effects of the bar on the Galactic thin and thick Disks”

Ponent: Dr. Giacomo Monari (Kapteyn Astronomical Institute, Groningen)

Lloc:  Aula 507 (Pere Pascual)

Data/Hora:  08.10.2014 / 12:00

Contacte: Mercè Romero (mromero @ ub.edu)

Resum: The study of kinematic groups of stars and streaming motions in the Solar Neighborhood has a long tradition. The interest on the subject has been amplified in modern times after the results of Hipparcos data and other surveys, and in the future we expect, with Gaia, a revolution in our understanding of the Milky Way.
The moving groups in the thin disk have been often associated with the disruption of open clusters or with the dynamical effects of the non-axisymmetric components of the Milky Way (bar, spiral arms).
However, when we speak about kinematical substructure in the thick disk, we usually think of the remnants of some accretion events. With the help of 3D test particle simulations of the Milky Way, I will show for the first time that the bar modifies significantly the velocity distribution both of thin and thick disk. I will define the concept of “resonant trapping”, and show the fraction of orbits trapped to several resonances with the bar stays constant in a wide range of heights from the Galactic plane. Moreover, the orbits trapped to the Outer Lindblad Resonance define an easily recognizable feature in velocity space. I will also show how the bar can induce negative velocity gradients in the extended Solar Neighborhood, even high from the Galactic plane, similarly to what is observed in the RAVE survey.