PI: Raghvendra Sahai, Jet Propulsion Laboratory, email@example.com
Address: 4800 Oak Grove Drive, Pasadena, CA 91109
CoI: Ken Hinkle, NOAO
CoI: Ben Sugerman, Goucher College
Title: Caught in the Act I: mapping the Collimated Outflows in V Hya, an AGB star evolving into a Bipolar Planetary Nebula
Abstract: The carbon star V Hydra is experiencing heavy mass loss as it undergoes the transition from AGB star to pre-planetary nebula (PN). This is possibly the earliest object known in this brief phase, which is so short that few nearby stars are likely to be caught in the act. Using STIS/HST, we discovered a high-velocity (>200 km/s) jet or blob of gas which was ejected only a few years ago from near (<0.3'') the star. We found time-variable high-velocity absorption features in the CO 4.6 micron vibration-rotation lines of V Hydra from a multi-epoch study; modelling shows that these are produced in compact clumps of outflowing gas with significant temperature gradients. Mm-wave interferometry with 3.5 arcsec resolution shows that the HV outflow is collimated and bipolar. We propose to use the Phoenix instrument to map the resonant-scattered CO 4.6 micron vibration-rotation line emission in order to probe the high-velocity outflows and circumstellar environment at radii of (0.5-few) arcsec with unprecedented resolution, and thus constrain the physical mechanisms which produce bipolar PNe from AGB stars.
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