David Nicholls (Australian National University, Australia)
The measurement of electron temperatures and metallicities in H II regions and Planetary Nebulae has, for several decades, presented a problem: results obtained using different techniques disagree. There have been numerous attempts to explain these discrepancies, but none has provided a satisfactory solution to the problem. In my talk I will discuss my recent work on the possibility that the electron energies in H II regions are not in equilibrium but are best described by kappa distributions, as found in many solar system plasmas. We find that the kappa distribution is able to explain discrepancies between recombination temperatures and direct electron temperatures. This discovery offers interesting opportunities in drawing together temperature and metallicity measurements in H II regions, and in estimating the degree to which the electron energies depart from equilibrium.