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A CO atlas of circumstellar envelopes of AGB and post-AGB stars

R.Neri tex2html_wrap_inline729 , C.Kahane tex2html_wrap_inline731 , R.Lucas tex2html_wrap_inline729 , V.Bujarrabal tex2html_wrap_inline733 , C.Loup tex2html_wrap_inline735
tex2html_wrap_inline729 Institut de RadioAstronomie Millimétrique, 300 rue de la Piscine, F-38406 Saint Martin d'Hères, France
tex2html_wrap_inline731 Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 9, France
tex2html_wrap_inline733 Observatorio Astronómico Nacional, Apartado 1143, E-28800 Alcalá de Henares, Spain
tex2html_wrap_inline735 Institut d'Astrophysique de Paris, CNRS, 98 bis bd Arago, 75014 Paris, France
Abstract: We present the results of a CO (J=1-0) and (J=2-1) survey on a sample of 46 objects classified as AGB and post-AGB stars. We have obtained fully sampled high resolution maps of their CO (J=1-0) emission by combining visibilities from the IRAM interferometer with short spacing observations from the IRAM 30m telescope. Properties of their circumstellar envelopes like fluxes, radii, and positions are derived from model fits to the visibilities and compared to the results obtained from CO (J=2-1) maps observed at the IRAM 30m telescope (Fig. 5). From the CO (J=1-0) observations we have derived mass loss rates for 38 stars and established an empirical relation between the CO photo dissociation radius of an envelope and the measured radius in the J=1-0 emission.



Figure 5: CIT 6 is a carbon-rich star, the most intense and one of the most extended sources in the atlas. The interferometric maps (lower panel) show the CO emission to be distributed in two components, in a compact one and in a weak and extended halo, both centred on the same position.

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