The effect of thermal non-equilibrium on kinetic nucleation

Context. Nucleation is considered to be the first step in dust and cloud formation atmospheres of asymptotic giant branch (AGB) stars, exoplanets, brown dwarfs. In these environments particles grow macroscopic sizes when gas phase species condense onto condensation nuclei (CCNs). Understanding processes CCNs AGB stars important because that formed their outflows enrich interstellar medium. Although widely used, validity chemical thermal equilibrium conditions debatable some highly dynamical astrophysical environments. Aims. We aim derive a kinetic nucleation model includes effects non-equilibrium by adopting different temperatures for nucleating species, quantify impact on nucleation. Methods. Forward backward rate coefficients are derived as part collisional theory ansatz. The endother-mic rates from law mass action non-equilibrium. consider elastic collisions drivers. Results. For homogeneous TiO 2 temperature 1250 K, we find differences cluster small 20 K increase larger clusters over an order magnitude. Conversely, around at 1000 can reduce Conclusions. Our results confirm prediction previous studies. Small non-equilibria cause significant change synthesis clusters. Therefore, it use models include describe where even present.