Multi-Wavelength Properties of Barred Galaxies in the Local Universe:
  Environment and evolution across the Hubble sequence
  We investigate possible environmental and morphological trends in the
$z\sim0$ bar fraction using two carefully selected samples representative of a
low-density environment (the isolated galaxies from the AMIGA sample) and of a
dense environment (galaxies in the Virgo cluster). Galaxies span a stellar mass
range from $10^8$ to $10^{12}$M$_{\odot}$ and are visually classified using
both high-resolution NIR (H-band) imaging and optical \texttt{rgb} images. We
find that the bar fraction in disk galaxies is independent of environment
suggesting that bar formation may occur prior to the formation of galaxy
clusters. The bar fraction in early type spirals ($Sa-Sb$) is $\sim$50%, which
is twice as high as the late type spirals ($Sbc-Sm$). The higher bar fraction
in early type spirals may be due to the fact that a significant fraction of
their bulges are pseudo-bulges which form via the buckling instability of a
bar. i.e. a large part of the Hubble sequence is due to secular processes which
move disc galaxies from late to early types. There is a hint of a higher bar
fraction with higher stellar masses which may be due to the susceptibility to
bar instabilities as the baryon fractions increase in halos of larger masses.
Overall, the $S0$ population has a lower bar fraction than the $Sa-Sb$ galaxies
and their barred fraction drops significantly with decreasing stellar mass.
This supports the notion that $S0s$ form via the transformation of disk
galaxies that enter the cluster environment. The gravitational harassment
thickens the stellar disks, wiping out spiral patterns and eventually erasing
the bar - a process that is more effective at lower galaxy masses.
