Galaxy Zoo: Bar Lengths in Nearby Disk Galaxies
  We present an analysis of bar length measurements of 3150 local galaxies in a
volume limited sample of low redshift (z < 0.06) disk galaxies. Barred galaxies
were initially selected from the Galaxy Zoo 2 project, and the lengths and
widths of the bars were manually drawn by members of the Galaxy Zoo community
using a Google Maps interface. Bars were measured independently by different
observers, multiple times per galaxy (>=3), and we find that observers were
able to reproduce their own bar lengths to 3% and each others' to better than
20%. We find a "color bimodality" in our disk galaxy population with bar
length, i.e., longer bars inhabit redder disk galaxies and the bars themselves
are redder, and that the bluest galaxies host the smallest galactic bars (< 5
kpc/h). We also find that bar and disk colors are clearly correlated, and for
galaxies with small bars, the disk is, on average, redder than the bar colors,
while for longer bars the bar then itself is redder, on average, than the disk.
We further find that galaxies with a prominent bulge are more likely to host
longer bars than those without bulges. We categorise our galaxy populations by
how the bar and/or ring are connected to the spiral arms. We find that galaxies
whose bars are directly connected to the spiral arms are preferentially bluer
and that these galaxies host typically shorter bars. Within the scatter, we
find that stronger bars are found in galaxies which host a ring (and only a
ring). The bar length and width measurements used herein are made publicly
available for others to use (http://data.galaxyzoo.org).
