  We investigate the electron temperature of the inner halo and nebular core
regions of NGC 6543, using archival Hubble Space Telescope (HST) Wide Field
Planetary Camera 2 (WFPC2) images taken through narrow band [O III] filters.
Balick et al. (2001) showed that the inner halo consists of a number of
spherical shells. We find the temperature of this inner halo to be much higher
(~15000 K) than that of the bright core nebula (~8500 K). Photo-ionization
models indicate that hardening of the UV radiation from the central star cannot
be the main source of the higher temperature in the halo region. Using a
radiation hydrodynamic simulation, we show that mass loss and velocity
variations in the AGB wind can explain the observed shells, as well as the
higher electron temperature.
