| Description |
We propose to perform a biased survey of Circumstellar Envelopes (CSE) in AGB and post-AGB stars in order to build a reference catalogue in two to three sub-millimetre and FIR CO transitions. The proposed observations will provide access to the emission of the envelope gas layers in the temperature range virgul100 to 2000K. These warm layers are fundamental to the field of stellar evolution because they are the regions where the acceleration of the gas takes place, and therefore where the envelopes are being formed. Because of the significant atmospheric opacity affecting ground-based observations at the corresponding wavelengths, this warm gas could never be probed in a systematic manner over large source samples. In fact, in some of the transitions emitting in this temperature regime, no observation at all is possible from the ground. The catalogue we are proposing to build will collect the emission of two CO transitions (J=5-4 and J=9-8) probing different layers of the warm gas in about 74 sources, and measure a high-J CO transition (J=14-13) in the 10 most intense sources of the sample. The total time to build this data-set is 35 hours. When eventually combined to the smaller sample collected by the GTKP HIFISTARS, this will form an unprecedented catalogue of over 100 AGB and post-AGB stars in two to three fundamental CO lines of the sub-millimetre and FIR domain, and offer a legacy data-base for the modelling of the shaping parameters of evolved stars. |
