The chemical evolution of molecular MHD winds from low-mass young stars
Despina Panoglou
Instituto de Astronomia, Geofísica e Ciências Atmosféricas
Universidade de São Paulo
Extensive modelling of atomic jets in the past showed that the temperature along the jet axis is 10000 K. With the advent of observations of molecular jets, and given that molecules cannot survive in such high temperatures, detailed thermochemical modelling of molecular disk winds was a necessary step towards understanding their nature. This work was the first attempt to show that the existence of molecules can as well be a result of chemical evolution of the disk material. To this aim, a model was constructed by imposing the dynamics prescribed by an MHD disk wind to a magnetic shock code incorporating an extended molecular chemical network. A radiation field was implemented, the momentum transfer rates between neutral and charged species were calculated in detail, and dust interactions with gas were taken into account. Photoreactions and collisional ionization maintain the ionization fraction high enough, so that the drift speed and temperature (2000 K) remain low. As a result, the molecular abundances are kept high, and molecules only partially dissociate in certain cases.