Survival of molecules in MHD disk winds

Abstract

Magnetohydrodynamical (MHD) models have been constructed and observations have been conducted thoroughly for atomic jets in the past. Observations of molecular jets implied the need of further modelling of jets that would include molecular chemistry. In this work we imposed a molecular chemical network on a self–similar steady state MHD disk wind, in order to study the origin and formation mechanisms of molecular jets. We calculated the radiation field as coming from the star and hot spots on its surface; this leads to an X-ray ionization rate, which, together with UV field induced photoreactions, raises the ionization fraction at the base of the flow. The main heating mechanism is the drag heating between charged and neutral particles, and after an initial increase of the temperature at low altitudes, it is balanced mainly by adiabatic and molecular cooling. Hence the temperature is maintained at low values, and molecules are indeed able to survive.