Abstract
We explored an efficient method to identify evolved stars with oxygen-prich envelopes in the late asymptotic giant branch (AGB) or post-pAGB phase of stellar evolution, which include a rare class of objects-pthe "water fountains (WF)." Our method considers the OH and H2O maser spectra, the near-pinfrared Q-pparameters (these are color indices accounting for the effect of extinction), and far-pinfrared AKARI colors. Here we first present the results of a new survey on OH and H2O masers. There were 108 color-pselected objects: 53 of them were observed in the three OH maser lines (1612, 1665, and 1667 MHz), with 24 detections (16 new for 1612 MHz); and 106 of them were observed in the H2O maser line (22 GHz), with 24 detections (12 new). We identify a new potential WF source, IRAS 19356+ 0754, with large velocity coverages of both OH and H2O maser emission. In addition, several objects with high-pvelocity OH maser emission are reported for the first time. The Q-pparameters as well as the infrared [09]-[18] and [18]-[65] AKARI colors of the surveyed objects are then calculated. We suggest that these infrared properties are effective in isolating aspherical from spherical objects, but the morphology may not necessarily be related to the evolutionary status. Nonetheless, by considering altogether the maser and infrared properties, the efficiency of identifying oxygen-prich late/post-pAGB stars could be improved.