The Planetary Nebulae Population in the Central Regions of M32: the
  SAURON view
  Extragalactic Planetary Nebulae (PNe) are not only useful as distance
signposts or as tracers of the dark-matter content of their host galaxies, but
constitute also good indicators of the main properties of their parent stellar
populations. Yet, so far, the properties of PNe in the optical regions of
galaxies where stellar population gradients can be more extreme have remained
largely unexplored, mainly because the detection of PNe with narrow-band
imaging or slit-less spectroscopy is considerably hampered by a strong stellar
background. Integral-field spectroscopy (IFS) can overcome this limitation, and
here we present a study of the PN population in the nearby compact elliptical
M32. Using SAURON data taken with just two 10-minutes-long pointings we have
doubled the number of known PNe within the effective radius of M32, detecting
PNe five times fainter than previously found in narrow-band images that
collected nearly the same number of photons. Furthermore, by carefully
accounting for the incompleteness of our survey we could conclude, despite
having only 15 sources, that the central PNe population of M32 is consistent
with the generally adopted shape for the PNe Luminosity Function and its
typical normalization observed in early-type galaxies. Finally, owing to the
proximity of M32 and to UV images taken with HST, we could identify the most
likely candidates for the central star of a subset of our detected PNe and
conclude that these stars are affected by substantial amounts of circumstellar
dust extinction, a finding that could reconcile the intriguing discrepancy
previously reported in M32 between model predictions and observations for the
later stages of stellar evolution. Considering the modest time investment on a
4m-class telescope that delivered these results, this work illustrates the
potential of future IFS studies for the central PNe population of early-type
galaxies.
