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The aim of this paper is to investigate how the new imaging Polarimeter andCoronograph (PolCor) at the Nordic Optical Telescope (NOT) can be used in thestudy of circumstellar structures around AGB stars, with the purpose ofpreparing for a study of a larger sample. We have observed two types of AGBstars using the PolCor instrument on the NOT: the binary S-type star W Aql andtwo carbon stars with detached shells, U Cam and DR Ser. The polarized lighttraces the dust distribution around the stars. From the polarimeter images thepolarized intensity, the polarization degree, and the polarization angle overthe images are calculated. The location and extent of dust structures areexamined in the images. The total dust mass and the dust-to-gas ratios of thedetached shells are also calculated. The images of the circumstellar envelopeof W Aql show what seems to be an elongated structure in the south-westdirection. The detached shells of U Cam and DR Ser are clearly seen in theimages. This is the first time the detached shell around DR Ser has beenimaged. The radii and widths of the shells are determined and found to be 7.9"and 7.6", and 0.9" and 1.2", for U Cam and DR Ser, respectively. This isconsistent with previous results. The dust masses of the feature south-west ofW Aql, and in the shells of U Cam and DR Ser are also estimated and found to be1x10^-6, 5x10^-7, and 2x10^-6 Msun, respectively. W Aql is a known binary andthe shape of the circumstellar envelope seems to be in line with what could beexpected from binary interaction on these scales. For the shells, the resultsare in agreement with previous investigations. Ages and formation time-scalesare also estimated for the detached shells and found to be consistent with thethermal-pulse-formation scenario.

Imaging the circumstellar dust around AGB stars with PolCor