| Description |
We propose to perform a biased survey of Circumstellar Envelopes (CSE) inAGB and post-AGB stars in order to build a reference catalogue in twoto three sub-millimetre and FIR CO transitions. The proposedobservations will provide access to the emission of the envelope gaslayers in the temperature range virgul100 to 2000K. These warm layers arefundamental to the field of stellar evolution because they are theregions where the acceleration of the gas takes place, and thereforewhere the envelopes are being formed. Because of the significantatmospheric opacity affecting ground-based observations at thecorresponding wavelengths, this warm gas could never be probed in a systematic manner over large source samples. In fact, in some of thetransitions emitting in this temperature regime, no observation at allis possible from the ground.The catalogue we are proposing to build will collect the emission oftwo CO transitions (J=5-4 and J=9-8) probing different layers of thewarm 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 timeto build this data-set is 35 hours. When eventually combinedto the smaller sample collected by the GTKP HIFISTARS, this will forman unprecedented catalogue of over 100 AGB and post-AGB stars in two tothree fundamental CO lines of the sub-millimetre and FIR domain, andoffer a legacy data-base for the modelling of the shaping parameters ofevolved stars. |
