Maser And Infrared Studies Of Oxygen-rich Late/post-asymptotic Giant Branch Stars And Water Fountains: Development Of A New Identification Method

published_or_final_versio

Maser Observations Of Westerlund 1 And Comprehensive Considerations On Maser Properties Of Red Supergiants Associated With Massive Clusters

published_or_final_versio

Exploration of a Relic Circumstellar Envelope in the "Water Fountain" Source IRAS 18286-0959

published_or_final_versio

Water Maser Survey on AKARI and IRAS Sources: A Search for "Low-velocity" Water Fountains

published_or_final_versio

A high velocity precessing jet from the water fountain IRAS 18286-0959 revealed by VLBA observations

Abstract book distributed at the conference venue at be downloaded at http://milkyway.sci.kagoshima-u.ac.jp/groups/eavws2010/We report the multi-epoch VLBA observations of 22.2 GHz water maser emission associated with the “water fountain” star IRAS 18286－0959. The detected maser emission peaks are distributed in the velocity range from -50 km/s to 150 km/s in the spectra. The distribution of over 70% of the identified maser features are found to be highly collimated along a spiral jet (jet 1) extended from southeast to northwest direction, and the rest of the features seem to trace out another spiral jet (jet 2) with different orientations, forming a “double-helix” pattern. A precessing jet model is proposed to fit the two jets independently. The coefficient of determination of the fitting is -0.85 for jet 1 and -0.51 for jet 2, indicating the model is reliable at least for jet 1. The precession periods and velocities are derived to be 60 years and 170 km/s for jet 1, 40 years and 152 km/s for jet 2, respectively. Owing to the difference between two sets of parameters, the two jets are probably originated from different driving sources visually close to each other. IRAS 18286－0959 is the second example of water fountain which has a collimated precessing outflow other than W 43A.The 3rd East Asia VLBI Wokshop, Kagoshima, Japan, 22-24 April 2010. In Abstracts of Oral Presentations of the 3rd East Asia VLBI Wokshop, 2010, p. 7