The effects of charge transfer on the thermal equilibrium of photoionized nebulae

Charge transfer can affect both the ionization and thermal balance of astro physical plasmas. Using the most recent rate coefficients and energy defect s, we calculate the heating/cooling rates for charge transfer reactions bet ween hydrogen and elements up to Z = 30. We incorporate these values into t he photoionization code CLOUDY. Results from models approximating a wide ra nge of astrophysical objects and conditions suggest that charge transfer ca n make a significant contribution to the heating near the H ionization fron t, particularly in objects with a hard ionizing continuum or enhanced abund ances. Charge transfer heating can also be important in regimes in which th e usual heating/cooling agents are suppressed, such as the emission-line cl ouds near quasars. We list those reactions that are most important for dete rmining the thermal balance, in the hopes of facilitating improved atomic d ata.