Developing asymmetries in AGB stars : occurrence, morphology and polarization of circumstellar Masers

My PhD research focuses on the maser emission which occurs in different regions of the circumstellar envelopes (CSEs) of evolved stars and can be studied at high angular resolution using radio interferometers. These masers are useful probes of the dynamics and kinematics of the outflow from AGB stars. Moreover, the masers can be important tracers of the magnetic field strength and morphology at various distances from the central stars. It is expected that the magnetic field plays an important role in transforming spherically symmetric AGB stars into a-spherical PNe. Theoretical modeling indicated that magnetically collimated jets may be responsible for the formation of the a-spherical PNe. We performed polarimetric observations of the masers (OH, H2O and SiO) in different classes of evolved stars using several radio interferometers as well as single dish radio and sub-mm telescopes, to study the role of the magnetic field throughout the AGB evolution.