On the connection between shape and stellar population in early-type
  galaxies
  We report on the discovery of a relation between the stellar mass $M^*$ of
early-type galaxies (hereafter ETGs), their shape, as parametrized by the
Sersic index $n$, and their stellar mass-to-light ratio $M^*/L$. In a 3D log
space defined by these variables the ETGs populate a plane surface with small
scatter. This relation tells us that galaxy shape and stellar population are
not independent physical variables, a result that must be accounted for by
theories of galaxy formation and evolution.
