On the galactic spin of barred disk galaxies
  We present a study of the connection between the galactic spin parameter
$\lambda_{d}$ and the bar fraction in a volume-limited sample of 10,674 disk
galaxies drawn from the Sloan Digital Sky Survey Data Release 7. The galaxies
in our sample are visually classified into galaxies hosting long or short bars,
and non-barred galaxies. We find that the spin distributions of these three
classes are statistically different, with galaxies hosting long bars with the
lowest $\lambda_{d}$ values, followed by non-barred galaxies, while galaxies
with short bars present typically high spin parameters. The bar fraction
presents its maximum at low to intermediate $\lambda_{d}$ values for the case
of long bars, while the maximum for short bars is at high $\lambda_{d}$. This
bi-modality is in good agreement with previous studies finding longer bars
hosted by luminous, massive, red galaxies with low content of cold gas, while
short bars are found in low luminosity, low mass, blue galaxies, usually gas
rich. In addition, the rise and fall of the bar fraction as a function of
$\lambda_{d}$, within the long-bar sample, shown in our results, can be
explained as a result of two competing factors: the self-gravity of the disk
that enhances bar instabilities, and the support by random motions instead of
ordered rotational motion, that prevents the formation/growth of bars.
