Energy implications of temperature fluctuations in photoionized plasma

We quantify the energy radiated through all the collisionally excited lines in a photoionized nebula which is permeated by temperature fluctuations. W e assume that these correspond to hot spots which are the results of an unk nown heating process distinct from the photoelectric heating. We consider a ll the effects of using a higher mean temperature (as compared to the equil ibrium temperature) due to the fluctuations not only on each emission line but also on the ionization state of the gas. If this yet unknown process wa s to radiate a fixed amount of energy, we find that the fluctuations should correlate with metallicity Z when it exceeds 0.7 solar. The excess energy radiated in the lines as a result of the fluctuations is found to scale pro portionally to their amplitude t(2). When referred to the total energy abso rbed through photoionization, the excess energy is comparable in magnitude to t(2).