Spatially-resolved NUV-r color of local star-forming galaxies and clues
  for quenching
  Using a sample of ~6,000 local face-on star-forming galaxies (SFGs), we
examine the correlations between the NUV-r colors both inside and outside the
half-light radius, stellar mass M* and S\'{e}rsic index n in order to
understand how the quenching of star formation is linked to galaxy structure.
For these less dust-attenuated galaxies, NUV-r is found to be linearly
correlated with Dn4000, supporting that NUV-r is a good photometric indicator
of stellar age (or specific star formation rate). We find that: (1) At
M*<10^{10.2}M_{\sun}, the central NUV-r is on average only~ 0.25 mag redder
than the outer NUV-r. The intrinsic value would be even smaller after
accounting for dust correction. However, the central NUV-r becomes
systematically much redder than the outer NUV-r for more massive galaxies at
M*>10^{10.2}M_{\sun}. (2) The central NUV-r shows no dependence on S\'{e}rsic
index n at M*<10^{10.2}M_{\sun}, while above this mass galaxies with a higher n
tend to be redder in the central NUV-r color. These results suggest that
galaxies with M*<10^{10.2}M_{\sun} exhibit similar star formation activity from
the inner R<R_{50} region to the R>R_{50} region. In contrast, a considerable
fraction of the M*>10^{10.2}M_{\sun} galaxies, especially those with a high n,
have harbored a relatively inactive bulge component.
