Interferometric Observations of Water Fountain Candidates

<p>Located between the AGB and PN phases of low- and intermediate-mass stars, &ldquo;Water Fountains&rdquo; (WFs) may provide significant clues on the shaping process of PNe. For example, WFs are considered the first manifestation of collimated mass-loss in evolved stars, given their high-velocity H2O masers. There are 15 WFs known up to date, and several others are considered candidates. They are identified by H2O maser emission with a velocity spread broader than that of the OH maser emission (typically between 10-30 km/s), the latter indicating the expansion velocity of the circumstellar envelopes of AGB stars. We aim to ascertain the WF nature of these candidates and investigate the spatial distribution of their H2O masers through interferometric observations. An increase in the number of WFs will help us to study and constrain their properties as a group.</p>