A relation between characteristic stellar age of galaxies and their
  intrinsic shape
  Stellar population and stellar kinematic studies provide unique but
complementary insights into how galaxies build-up their stellar mass and
angular momentum. A galaxy's mean stellar age reveals when stars were formed,
but provides little constraint on how the galaxy's mass was assembled. Resolved
stellar dynamics trace the change in angular momentum and orbital distribution
of stars due to mergers, but major mergers tend to obscure the effect of
earlier interactions. With the rise of large multi-object integral field
spectroscopic (IFS) surveys, such as SAMI and MaNGA, and single-object IFS
surveys (e.g., ATLAS$^{\rm{3D}}$, CALIFA, MASSIVE), it is now feasible to
connect a galaxy's star formation and merger history on the same resolved
physical scales, over a large range in galaxy mass, and across the full range
of optical morphology and environment. Using the SAMI Galaxy Survey, here we
present the first study of spatially-resolved stellar kinematics and global
stellar populations in a large IFS galaxy survey. We find a strong correlation
of stellar population age with location in the ($V / \sigma$,
$\epsilon_{\rm{e}}$) diagram that links the ratio of ordered rotation to random
motions in a galaxy to its observed ellipticity. For the large majority of
galaxies that are oblate rotating spheroids, we find that characteristic
stellar age follows the intrinsic ellipticity of galaxies remarkably well. This
trend is still observed when galaxies are separated into early-type and
late-type samples.
