Crowded-field 3D Spectrophotometry of PNe in Local Group Galaxies
M.M. Roth, D. Schoenberner, T. Becker, M. Steffen
Astrophysikalisches Institut Potsdam, Germany
Spectrophotometry of extragalactic planetary nebulae in high
surface-brightness regions of nearby galaxies is notoriously difficult
because of the problem of accurately subtracting the local background of
unresolved stars and gaseous emission of the ISM. Conventional slit
spectroscopy is not very well suited for providing a good estimate of
the two-dimensional surface brightness distribution in the continuum,
absorption lines, and superimposed emission lines from all of these
background sources. Consequently, the first abundance studies of
background-limited extragalactic PNe seem to have significantly suffered
from systematic errors related to the background subtraction problem.
We present results from a prototype study with PNe in the bulge of
M31, using Integral Field (3D) Spectroscopy to overcome these
observational problems, arguing that the method is superior to
slit spectroscopy and the ideal tool for spectrophotometry of
faint sources in crowded field environments. We also present some
recent results from observations of PN candidates in the Leo A and
Sextans B galaxies using the PMAS 3D instrument at Calar Alto.