IRAS 17150-3224: a young, optically bipolar, proto-planetary nebula

We have carried out optical, near-infrared and CO and OH observations of the cool infrared source IRAS 17150-3224. We argue that the source is a young protoplanetary nebula. Its spectral type is G2I. From radiative transfer modelling we find that the AGB wind terminated less than ∼ 150 yr ago. We derive a mass loss rate on the AGB of M ∼ 4.10 −5 M ○ .yr −1 . The optical observations show a bipolar reflection nebula, and indicate the presence of a dust torus which inhibits a direct view of the central star, but allows illumination of the reflection lobes. The OH maser spectra suggests that at large distances from the star the circumstellar shell is more or less spherical, which indicates that a transition from spherically symmetric to equatorial outflow took place less than ∼ 10 3 yr ago