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A molecular jet in the pre-planetary nebula IRAS19134+2131

A molecular jet in the pre-planetary nebula IRAS19134+2131

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A molecular jet in the pre-planetary nebula IRAS19134+2131

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  1. 8th EVN Symposium on 27 Sep. 2006 A molecular jet in the pre-planetary nebula IRAS19134+2131 Hiroshi Imai (Kagoshima Univ.) Mark Morris (UCLA) Raghvendra Sahai (JPL/NASA)

  2. From spherically symmetric to asymmetric flow Egg Nebula ⓒNASA Betelgeuse ⓒNASA • When/how is a bipolar jet launched in the final stellar evolution?

  3. “Water fountains” in AGB/post-AGB phases W43A • Vexp(H2O)> Vexp(OH) ~ 30 km/s • OH12.8-0.9 (Boboltz & Marvel 2005) • W43A (Imai et al. 2002, 2005; Vlemmings et al. 2006) • IRAS19134+2131 (Imai et al. 2004) • IRAS16342-3814 (Sahai et al. 1999; Morris et al. 2003) IRAS 19134+2131 IRAS 16342-3814 Water fountains (Likkel et al. 1992)

  4. 2MASS image IRAS19134+2131 • A kinematic distance was estimated to be ~16 kpc. • T~190 K envelope • Bipolar nebulosity in an HST image • Preplanetary nebula (PPN) phase (since Sahai et al. 2005) • No SiO, OH maser emission • F(H2O) < 3Jy • Long-term integration/ high precision astrometry in phase-referencing technique

  5. Maser spatio-kinematics (VLA) 500 AU at 8 kpc

  6. Maser relative proper motions • Dynamical age ~ 40 years • Duration of a water fountain:< 100 years • Transition from AGB (W43A) to pre-planetary nebula (IRAS 19134+2131)

  7. High precision maser astrometry J1625+2106: 2.5 deg away, ~1.9 Jy Galactic rotation

  8. Galactic rotation and annual parallax! Mean motion of 3 maser features

  9. Annual parallax distance:8.0 kpc +0.9 -0.7

  10. Location and kinematicsin the Galaxy • Location in the Galaxy (Rsun≡ 8.0 kpc Θ sun≡ 218 km/s) • Velocity in the Galaxy • A member of the “thick component” in the Galaxy. • If kicked from the Galactic plane in the star formation process: t ~5x107years (> 1.3x107years for Vz<50 km/s) • Bipolar PNe and OH/IR stars tend to be members of the “thin component” in the Galaxy.

  11. Summary • Duration of the water fountains:<100 yr • During the water fountain activity, transition from AGB to post-AGB phase may occur. • Likely jets in PNe have already been formed in the water fountains. • My prediction: quenching of a water fountain before my own retirement/death. • Direct measurement of galactic rotations and distances • D~8kpc: consistent between annual parallax and advanced kinematic distances • Vθ~120 km/s, z=650 pc: member of the thick component.