The ionized gas at the center of IC 10: A possible localized chemical
  pollution by Wolf-Rayet stars
  We present results from integral field spectroscopy with the Potsdam
Multi-Aperture Spectrograph at the 3.5m telescope at Calar Alto Observatory of
the intense star-forming region [HL90] 111 at the center of the starburst
galaxy IC 10. We have obtained maps with a spatial sampling of 1" x 1" = 3.9 pc
x 3.9 pc of different emission lines and analyzed the extinction, physical
conditions, nature of the ionization, and chemical abundances of the ionized
gas, as well determined locally the age of the most recent star-formation
event. By defining several apertures, we study the main integrated properties
of some regions within [HL90] 111. Two contiguous spaxels show an unambiguous
detection of the broad He II 4686 emission line, this feature seems to be
produced by a single WNL star. We also report a probable N and He enrichment in
the precise spaxels where the WR features are detected. The enrichment pattern
is roughly consistent with that expected for the pollution of the ejecta of a
single or a very small number of WR stars. Furthermore, this chemical pollution
is very localized (~2"~7.8 pc) and it should be difficult to detect in
star-forming galaxies beyond the Local Volume. We also discuss the use of the
most-common empirical calibrations to estimate the oxygen abundances of the
ionized gas in nearby galaxies from 2D spectroscopic data. The ionization
degree of the gas plays an important role when applying these empirical
methods, as they tend to give lower oxygen abundances with increasing
ionization degree.
