A recently generated theoretical line list of C II dielectronic recombination
lines together with observational data gathered from the literature is used to
investigate the electron temperature in a range of astronomical objects, mainly
planetary nebulae. The electron temperature is obtained by a least-squares
optimisation using all the reliable observed lines in each object. In addition,
the subset of lines arising directly from autoionising states is used to
directly determine the free-electron energy distribution which is then compared
with various theoretical possibilities. The method described here can
potentially determine whether there are departures from Maxwell-Boltzmann
distributions in some nebulae, as has been recently proposed. Using published
observations of the three planetary nebulae where the relevant lines are
recorded, we find that the data are best matched by Maxwell-Boltzmann
distributions but that the uncertainties are sufficiently large at present that
kappa-distributions or two-component nebular models are not excluded.Comment: 13 pages, 13 figures, 3 table
