Hiroshi Imai, Sze-Ning Chong, Jin-Hua He, Jun-ichi Nakashima, Chih-Hao Hsia, Takeshi Sakai, Shuji Deguchi, Nico Koning
We observed four "water fountain" sources in the CO J=3-2 line emission with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope in 2010-2011. The water fountain sources are evolved stars that form high-velocity collimated jets traced by water maser emission. The CO line was detected only from IRAS 16342-3814. The present work confirmed that the ^{12}CO to ^{13}CO line intensity ratio is ~1.5 at the systemic velocity. We discuss the origins of the very low ^{12}CO to ^{13}CO intensity ratio, as possible evidence for the "hot-bottom burning" in an oxygen-rich star, and the CO intensity variation in IRAS 16342-3814.
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http://arxiv.org/abs/1204.2899
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