There is a class of binary post-AGB stars that are surrounded by Keplerian disks and that often present outflows resulting from gas escaping from the disk. To date there are seven sources that have been studied in detail through interferometric millimeter-wave maps of CO lines. For the cases of the Red Rectangle, IW Carinae, IRAS 08544-4431, and AC Herculis, it is found that 90% of the total nebular mass is located in the disk: these are the disk-dominated sources. On the contrary, our maps and modeling of 89 Herculis, IRAS 19125+0343, and R Scuti, which allowed us to study their morphology, kinematics, and mass distribution, suggest that in these sources the outflow is the dominant component of the nebula, resulting in a new subclass nebulae around binary post-AGB stars: the outflow-dominated ones. Besides CO, the molecular content of this kind of sources was barely known. We also present the first single-dish molecular survey. Our results allow us to classify our sources as O- or C-rich. The molecular content is relatively low in nebulae around binary post-AGB stars, as their molecular lines and abundances are particularly weaker compared with AGB stars and other post-AGB stars.

{"references": ["Gallardo Cava et al. 2021", "Gallardo Cava et al submitted"]}