Letter to the Editor
University of Vienna, Department of Astronomy, Türkenschanzstraße 17, 1180 Vienna, Austria e-mail: email@example.com
2 Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium
3 Institute of Computer Vision and Graphics, TU Graz, Inffeldgasse 16/II, A-8010 Graz, Austria
4 Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium
5 Sterrenkundig Instituut Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 Amsterdam, The Netherlands
Accepted: 12 May 2010
Detached circumstellar dust shells are detected around three carbon variables using Herschel-PACS. Two of them are already known on the basis of their thermal CO emission and two are visible as extensions in IRAS imaging data. By model fits to the new data sets, physical sizes, expansion timescales, dust temperatures, and more are deduced. A comparison with existing molecular CO material shows a high degree of correlation for TT Cyg and U Ant but a few distinct differences with other observables are also found.
Key words: stars: AGB and post-AGB / stars: carbon / stars: evolution / stars: mass-loss / infrared: stars
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Table 1 and Figs. 3 to 5 are only available in electronic form at http://www.aanda.org
© ESO, 2010