Program: GS-2005A-C-8

The detailed physics responsible for mass loss from evolved late-type stars remains unknown after half a century of study. Mapping the inner wind regions around these stars and determining their thermodynamic properties allow us to constrain potential mass loss mechanisms. Microwave emission lines and optical resonance lines have been used to image circumstellar shells on the sky. A new technique recently exploited by us is to image resonance scattering from infrared vibration-rotational carbon monoxide lines. This technique explores the inner shell region providing complementary information to other techniques. Infrared CO mapping is especially powerful since the excitation, gas temperature and column densities can be determined, and importantly also their spatial gradients. We propose to use the unique Phoenix-Gemini combination to do this. Information on the velocity structure and the development of clumps in the flow can also be determined. The present proposal focuses on the study of the shells around 3 late-type giants ($\alpha$~Ori, L$^2$~Pup and R~Hya) and is part of a study of the connection between the wind acceleration region and the outer shells.