VLA observations of the "water fountain" IRAS 16552-3050

TL;DR

This paper reports VLA observations of water maser emission in IRAS 16552-3050, identifying it as a water fountain source with high-velocity bipolar jets, likely heavily obscured and possibly tracing a precessing jet structure.

Contribution

First detailed VLA study of IRAS 16552-3050 confirming its classification as a water fountain source with unique maser and jet characteristics.

Findings

Water maser emission shows ~170 km/s velocity spread.

Bipolar distribution with ~0.08" separation.

Lacks optical and near-IR counterparts, indicating heavy obscuration.

Abstract

We present Very Large Array (VLA) observations of the water 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 water 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 water 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 water maser emission in IRAS 16552-3050 could be tracing a rapidly precessing bipolar jet.