Looking for new water-fountain stars

Abstract

We carried out simultaneous observations of H2O and OH masers, and radio continuum at 1.3 cm with the Karl G. Jansky Very Large Array (VLA) towards 4 water-fountain candidates. Water fountains (WFs) are evolved stars, in the AGB and post-AGB phase, with collimated jets traced by high-velocity H2O masers. Up to now, only 15 sources have been confirmed as WFs through interferometric observations. We are interested in the discovery and study of new WFs. A higher number of these sources is important to understand their properties as a group, because they may represent one of the first manifestations of collimated mass-loss in evolved stars. These observations will provide information about the role of magnetic fields in the launching of jets in WFs. Our aim is to ascertain the WF nature of these candidates, and investigate the spatial distribution of the H2O and OH masers.

Interferometric Observations of the Water Fountain Candidates OH 16.3−3.0 and IRAS 19356+0754

“…1c) does not show conclusive evidence for a collimated jet. It is still possible that the source is a WF, but with the outflow lying close to the plane of the sky, or a different kind of WF, e.g., with a less massive progenitor or with a relatively younger age (Uscanga et al 2019). We did not detect H 2 O maser emission in I19356 with a 3σ detection limit of 17.7 mJy, despite a previous single-dish detection with a flux density of ∼ 0.2 Jy and rms of 10 mJy (Yung et al 2014).…”