| Description |
Molecular spectroscopy at sub-mm and FIR wavelengths is an extremely powerful
tool to investigate the latest stages of stellar evolution. The process of mass
loss from evolved stars is not well understood, and molecular emission
offers a unique avenue to trace the kinematics and structures of such objects, from AGB stars and their
successors, Planetary Nebulae (PN), to massive supergiants. In addition, circumstellar
shells of evolved stars foster a remarkable chemistry, producing unusual molecular species
not easily observed in other environments, including long carbon chains, anions, metal-bearing
molecules, and phosphorus compounds. The mechanisms by which this chemical synthesis
takes place, its relationship to dust formation, and its evolution during
the AGB and post AGB-phases, are all important questions that have yet
to be understood. This proposal and the related other proposals
submitted by our collaborators seek to answer these
questions. Through the study of the emission from specific species
combined with selected spectral surveys towards the PN NGC7027,
we aim at understanding more specifically the physics taking place in
the beginning of the PN stage, more exactly to precise the physical
conditions ruling the molecular envelope, the ionized region and the
thin interface between both, i.e. the PDR, through the quantification of
the UV and shocks influence. |
