Water Fountains in Pre-Planetary Nebulae: The Case of IRAS16342–3814

Abstract

AbstractWe present a brief review of Very Long Baseline Array (VLBA) observations of water masers in the so-called water fountain pre-planetary nebulae, and report on new VLBA and Very Large Array (VLA) data for the water masers in the prototypical water fountain source IRAS16342–3814, taken approximately monthly in 2008–2009. A new and very strong water maser is found at an LSR velocity of −3 km s−1, which is offset from the central (likely stellar) velocity. The new VLBA observations still show a similar general structure as was observed in 2002, but there are details which are difficult to explain.