Unravelling the chemical inhomogeneity of PNe with VLT FLAMES   integral-field unit spectroscopy
  Recent weak emission-line long-slit surveys and modelling studies of PNe have convincingly argued in favour of the existence of an unknown component in the planetary nebula plasma consisting of cold, hydrogen-deficient gas, as an explanation for the long-standing recombination-line versus forbidden-line temperature and abundance discrepancy problems. Here we describe the rationale and initial results from a detailed spectroscopic study of three Galactic PNe undertaken with the VLT FLAMES integral-field unit spectrograph, which advances our knowledge about the small-scale physical properties, chemical abundances and velocity structure of these objects across a two-dimensional field of view, and opens up for exploration an uncharted territory in the study and modelling of PNe and photoionized nebulae in general. 
Y. G. Tsamis (UCL), J. R. Walsh (ESO), D. Pequignot (Meudon), M. J.   Barlow (UCL), X.-W. Liu (Beijing), I. J. Danziger (Tri...