Arm-interarm gas abundance variations explored with MUSE: the role of
  spiral structure in the chemical enrichment of galaxies
  Spiral arms are the most characteristic features of disc galaxies, easily
distinguishable due to their association with ongoing star formation. However,
the role of spiral structure in the chemical evolution of galaxies is unclear.
Here we explore gas-phase abundance variations between arm and interarm regions
for a sample of 45 spiral galaxies using high spatial resolution VLT/MUSE
Integral Field Spectroscopy data. We report the presence of more metal-rich HII
regions in the spiral arms with respect to the corresponding interarm regions
for a large subsample of galaxies ($45-65\%$ depending on the adopted
calibrator for the abundance derivation). A small percentage of the sample is
observed to display the opposite trend, that is, more metal-poor HII regions in
the spiral arms compared to that of the interarms ($5-20\%$ depending on the
calibrator). We investigate the dependence of the variations with three galaxy
properties: the stellar mass, the presence of bars, and the flocculent/grand
design appearance of spiral arms. In all cases, we observe that the
arm-interarm abundance differences are larger (positive) in more massive and
grand-design galaxies. This is confirmed by an analogous spaxel-wise analysis,
which also shows a noticeable effect of the presence of galactic bars, with
barred systems presenting larger (positive) arm-interarm abundance variations
than unbarred systems. The comparison of our results with new predictions from
theoretical models exploring the nature of the spirals would highly impact on
our knowledge on how these structures form and affect their host galaxies.
