Orbital properties of binary post-AGB stars

Abstract We present the results of a decade-long radial velocity monitoring campaign of post-AGB binaries. We derived the orbital elements of 33 post-AGB binaries. We find a companion mass distribution centred around 1.09 M ⊙ with a very large spread. All the post-AGB binaries in our sample are expected to have filled their Roche lobes while at giant dimensions. Current binary evolution models are unable to explain the observed distribution of orbits.