PI: Raghvendra Sahai, Jet Propulsion Laboratory, firstname.lastname@example.org
Address: 4800 Oak Grove Drive, Pasadena, CA 91109
CoI: Ken Hinkle, NOAO
Title: Caught in the Act II: A High-Velocity Outflow in \pi^1Gru, an S-type AGB star evolving into a Bipolar Planetary Nebula
Abstract: The S-star \pi^1Gru has experienced heavy mass loss, and from the presence of a high-velocity bipolar outflow detected via mm-wave CO emission lines, it appears likely that it has now begun its transition from an AGB star towards the planetary nebula phase. \pi^1Gru and its well-studied carbon-star cousin, V Hya, are the earliest two object known in this brief phase, which is so short that few nearby stars are likely to be caught in the act. Interferometric mm-wave observations show that \pi^1Gru possesses a large equatorial disk and high-velocity polar outflow structure like V Hya. We now propose to (i) search for high-velocity absorption features and (ii) map the resonant-scattered emission, in the CO 4.6 micron vibration-rotation lines towards \pi^1Gru. These data will allow us to probe the spatio-kinematic structure of the high-velocity outflows and disk at radii of (0.5-few) arcsec with unprecedented angular resolution, and determine the mass- outflow rates. These data will be invaluable for building models of how fast jets sculpt AGB mass-loss envelopes to produce bipolar planetary nebulae.
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