The dynamics of the {\gamma} Vel cluster and nearby Vela OB2 association
  The kinematics of low-mass stars in nearby OB associations can provide clues
about their origins and evolution. Combining the precise positions, proper
motions and parallaxes given in the second Gaia Data Release with radial
velocity measurements obtained with the Hermes spectrograph at the
Anglo-Australian Telescope, we have an opportunity to study in detail the
kinematics of low-mass stars belonging to the nearby $\gamma$ Vel cluster and
the Vela OB2 association it is projected against. The presence of lithium is
used to confirm the youth of our targets. We separate our sample into the
cluster and association populations based on the membership probabilities of
Jeffries et al. 2014, their parallaxes, and kinematics. We find strong evidence
for expansion in the OB association population with at least 4$\sigma$
significance along all three axes, though the expansion is notably anisotropic.
We discuss these results in the context of cluster and association dispersal
theories.
