CO J = 3-2 emission from the "water fountain" sources IRAS 16342-3814 and IRAS 18286-0959

Abstract

We observed CO J = 3-2 emission from "water-fountain" sources, which exhibit high-velocity collimated stellar jets traced by H 2O maser emission, with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope. We detected CO emission from two sources: IRAS 16342-3814 and IRAS 18286-0959. The IRAS 16342-3814 CO emission exhibits a spectrum that could be well fit to a Gaussian profile, rather than to a parabolic profile, with a velocity width (FWHM) of 158 ± 6 km s -1 and an intensity peak at V LSR= 50 ± 2km s -1. The mass-loss rate of the star is estimated to be ∼ 2.9 x 10 -5 M ⊙ yr -1. Our morpho-kinematic models suggest that the CO emission is optically thin, and associated with a bipolar outflow rather than with a (cold and relatively small) torus. The IRAS 18286-0959 CO emission has a velocity width (FWHM) of 3.0 ± 0.2 km s -1 smaller than typically seen in AGB envelopes. The narrow velocity width of the CO emission suggests that it originates from either an interstellar molecular cloud or a slowly-rotating circumstellar envelope that harbors the H 2O maser source. © 2009. Astronomical Society of Japan.