VLA Observations of the “Water Fountain” IRAS 16552−3050

Abstract

We present Very Large Array (VLA) observations of the maser emission towards IRAS 16552-3050. The maser emission shows a velocity spread of ~170 km/s, and a bipolar distribution with a separation between the red and blueshifted groups of ~0.08. These observations and the likely post-AGB nature of the source indicate that IRAS 16552-3050 can be considered as a member of the water fountain class of sources (evolved stars showing H2O maser emission with a velocity spread $\ga$ 100 km/s, probably tracing collimated jets). The maser emission in IRAS 16552-3050 does not seem to be associated with with any known optical counterpart. Moreover, this source does not have a near-IR 2MASS counterpart, as it happens in about half of the fountains known. This suggests that these sources tend to be heavily obscured objects, probably with massive precursors ($\ga 4-5$ M$_\odot$). We suggest that the maser emission in IRAS 16552-3050 could be tracing a rapidly precessing bipolar jet.