The Close AGN Reference Survey (CARS): Comparative analysis of the
  structural properties of star-forming and non-star-forming galaxy bars
  The absence of star formation in the bar region that has been reported for
some galaxies can theoretically be explained by shear. However, it is not clear
how star-forming (SF) bars fit into this picture and how the dynamical state of
the bar is related to other properties of the host galaxy. We used
integral-field spectroscopy from VLT/MUSE to investigate how star formation
within bars is connected to structural properties of the bar and the host
galaxy. We derived spatially resolved H$\alpha$ fluxes from MUSE observations
from the CARS survey to estimate star formation rates in the bars of 16 nearby
($0.01 < z < 0.06$) disc galaxies with stellar masses between $10^{10} M_\odot$
and $10^{11} M_\odot$. We further performed a detailed multicomponent
photometric decomposition on images derived from the data cubes. We find that
bars clearly divide into SF and non-star-forming (non-SF) types, of which eight
are SF and eight are non-SF. Whatever the responsible quenching mechanism is,
it is a quick process compared to the lifetime of the bar. The star formation
of the bar appears to be linked to the flatness of the surface brightness
profile in the sense that only the flattest bars $\left(n_\mathrm{bar} \leq
0.4\right)$ are actively SF $\left(\mathrm{SFR_{b}} > 0.5 M_\odot
\mathrm{yr^{-1}}\right)$. Both parameters are uncorrelated with Hubble type. We
find that star formation is 1.75 times stronger on the leading than on the
trailing edge and is radially decreasing. The conditions to host non-SF bars
might be connected to the presence of inner rings. Additionally, from testing
an AGN feeding scenario, we report that the star formation rate of the bar is
uncorrelated with AGN bolometric luminosity. The results of this study may only
apply to type-1 AGN hosts and need to be confirmed for the full population of
barred galaxies.
