So far, only one rotating disk has been clearly identified and studied in AGB
or post-AGB objects (in the Red Rectangle), by means of observations with high
spectral and spatial resolution. However, disks are thought to play a key role
in the late stellar evolution and are suspected to surround many evolved stars.
We aim to extend our knowledge on these structures.
We present interferometric observations of CO J=2-1 emission from the nebula
surrounding the post-AGB star AC Her, a source belonging to a class of objects
that share properties with the Red Rectangle and show hints of Keplerian disks.
We clearly detect the Keplerian dynamics of a second disk orbiting an evolved
star. Its main properties (size, temperature, central mass) are derived from
direct interpretation of the data and model fitting. With this we confirm that
there are disks orbiting the stars of this relatively wide class of post-AGB
objectsComment: 4 pages, 3 figure