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We present the first optical images of scattered light from large, detachedgas/dust shells around two carbon stars, R Scl and U Ant, obtained in narrowband filters centred on the resonance lines of neutral K and Na, and in a Str.b filter (only U Ant). They confirm results obtained in CO radio lineobservations, but also reveal new and interesting structures. Towards R Scl thescattering appears optically thick in both the K and Na filters, and bothimages outline almost perfectly circular disks with essentially uniformintensity out to a sharp outer radius of 21". These disks are larger -- byabout a factor of two -- than the radius of the detached shell which has beenmarginally resolved in CO radio line data. In U Ant the scattering in the Kfilter appears to be, at least partially, optically thin, and the image isconsistent with scattering in a geometrically thin (3") shell (radius 43") withan overall spherical symmetry. The size of this shell agrees very well withthat of the detached shell seen in CO radio line emission. The scattering inthe Na filter appears more optically thick, and the image suggests the presenceof at least one, possibly two, shells inside the 43" shell. There is noevidence for such a multiple-shell structure in the CO data, but this can bedue to considerably lower masses for these inner shells. Weak scatteringappears also in a shell which is located outside the 43" shell. The presentdata do not allow us to conclusively identify the scattering agent, but weargue that most of the emission in the K and Na filter images is to due toresonance line scattering, and that there is also a weaker contribution fromdust scattering in the U Ant data. Awaiting new observational data, ourinterpretation must be regarded as tentative.Comment: 14 pages, 11 figures, to be published in A&

Imaging of detached shells around the carbon stars R Scl and U Ant through scattered stellar light