Integral field spectroscopy of HII regions in M33
  Integral field spectroscopy (IFS) is presented for star forming regions in
M33. A central area of 300 x 500 pc^2 and the external HII region IC 132, at a
galactocentric distance {\sim} 19arcmin (4.69 kpc) were observed with the
Potsdam Multi Aperture Spectrophotometer (PMAS) instrument at the 3.5 m
telescope of the Calar Alto Hispano- Alem\'an observatory (CAHA). The spectral
coverage goes from 3600 A to 1{\mu}m to include from [OII]{\lambda}3727 A to
the near infrared lines required for deriving sulphur electron temperature and
abundance diagnostics. Local conditions within individual HII regions are
presented in the form of emission line fluxes and physical conditions for each
spatial resolution element (spaxel) and for segments with similar H{\alpha}
surface brightness. A clear dichotomy is observed when comparing the central to
outer disc HII regions. While the external HII region has higher electron
temperature plus larger H{\beta} equivalent width, size and excitation, the
central region has higher extinction and metal content. The dichotomy extends
to the BPT diagnostic diagrams that show two orthogonal broad distributions of
points. By comparing with pseudo-3D photoionization models we conclude that the
bulk observed differences are probably related to a different ionization
parameter and metallicity. Wolf-Rayet features are detected in IC 132, and
resolved into two concentrations whose integrated spectra were used to estimate
the characteristic number of WR stars. No WR features were detected in the
central HII regions despite their higher metallicity.
