The effect of the environment on the stellar mass - size relation of
  present-day galaxies
  To study how the environment can influence the relation between stellar mass
and effective radius of nearby galaxies (z < 0.12), we use a mass-complete
sample extracted from the NYU-Value Added Catalogue. This sample contains
almost 232000 objects with masses up to $3\times10^{11}M_{\odot}$. For every
galaxy in our sample, we explore the surrounding density within 2 Mpc using two
different estimators of the environment. We find that galaxies tend to be
larger in the field than in high density regions. This effect is more
pronounced for late-type morphologies (~7.5% larger) and especially at low
masses ($M < 2\times10^{10}M_{\odot}$), although early-type galaxies also show
differences (~3.5%). The environment also leaves a subtle imprint in the
scatter of the stellar mass-size relation. This scatter is larger in low
density regions than in high density regions for both morphologies, on average
~3.5% larger for early-type and ~0.8% for late-type galaxies. Late-type
galaxies with low masses ($M<2\times10^{10}M_{\odot}$) show the largest
differences in the scatter among environments. The scatter is ~20% larger in
the field than in clusters for these objects. Our analysis suggest that
galaxies in clusters form earlier than those in the field. In addition, cluster
galaxies seem to be originated from a more homogeneous family of progenitors.
