AGB ENVELOPES, IRAM · Circumstellar envelopes of AGB and young post-AGB stars

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Project objective

We will perform systematic high-quality observations of low-energy molecular lines with the IRAMinterferometer, in a wide sample of AGB and post-AGB objects. Our purpose is to study in depth thecircumstellar envelopes of these objects, their effects on the stellar evolution, with particular attention to the structure of the AGB envelopes and to the irruption of the post-AGB winds in them. We will in particular determine1) the radius of the CO envelope, which is a basic parameter to understandphotodissociation effects and to interpret CO data in terms of mass-loss rate;2) the eventual existence of a seed of the future asymmetry in the inner AGB envelopes;3) the transition from spherical structure + isotropic expansion to axial symmetry and kinematics, just at the end of thigh phase; and4) the existence of brightness variations with radius that should reveal the variations of mass-loss rates, expected during the studied phases, and with angle, related to departures from spherical symmetry. For that we will develop specific models to infer the excitation conditions and thespatio-kinematic distribution of the AGB and young post-AGB envelopes. Finally, we will compile all data in a high-quality molecular data archive of AGB and post-AGB circumstellar envelopes. The applicant will develop an important scientific training, since these scientific results are expected tube crucial for the understanding of the stellar evolution. The expected high-quality data will allow addressing new questions on the circumstellar envelopes, and developing new models to better understand the observations. The applicant will acquire moreover high-quality technical knowledge, very valuable for the European astronomical community, given its involvement in the worldwide main observational project of the future, ALMA.

Original text from CORDIS.

Participants

• INSTITUT DE RADIOASTRONOMIE MILLIMETRIQUE · SAINT MARTIN D'HERESCoordinatorCity levelFrance

Links

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