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Panoramic Views of Water Fountain Sources

A Neapolitan of Masers: Variability, Magnetism and VLBI 20 May 2013, CSIRO CASS, Australia. Panoramic Views of Water Fountain Sources. Hiroshi Imai Graduate School of Science and Engineering Kagoshima University. Betelgeuse ( Mira variable ) ⓒ NASA.

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Panoramic Views of Water Fountain Sources

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  1. A Neapolitan of Masers: Variability, Magnetism and VLBI 20 May 2013, CSIRO CASS, Australia Panoramic Views of Water Fountain Sources Hiroshi Imai Graduate School of Science and Engineering Kagoshima University

  2. Betelgeuse (Mira variable) ⓒ NASA Water fountainhighly collimated, fast, stellar, molecular jet from AGB to post-AGB star, from spherical symmetric to asymmetric circumstellar envelope W43A (OH/IR star) water fountain Deguchi et al. 2007 H2O maser spectrum (Likkel et al. 1992) Egg Nebula (post-AGB star) ⓒ NASA

  3. Masers in water fountains Dynamical centers within 70 AU Systemic velocities within 3 km/s H2O and OH masers (Imai et al. 2002) SiO and H2O masers (Imai et al. 2005) SPITZER/GLIMPSE image around W43A (Deguchi et al. 2007) VLT 11.85 micron image of W43A (Lagadec et al. 2011)

  4. Open issues of water fountains • Mechanism of stellar jet launch • See Vlemmings’s talk about magnetic field • Mechanism of planetary nebula shaping by jet • Character of stellar system: single star v.s. binary • Dynamical time scales: tdyn(H2O)=l/vexp<100 yr, But equal to true ages? Can we see evolution/devolution? • Precessing jets? Recurrent jet ignitions? • Main-sequence mass and evolutionary phase of host star? • What is low-velocity H2O maser components?

  5. Three new aspects in this talk • Luminosities andsecular motions of the water fountain systems • Astrometry with VLBA and VERA • Thermal molecular emission (12CO, 13CO) • High velocity molecular component • Hot-bottom burning in nucleosynthesis • Kinematics of low velocity H2O maser components • Relic AGB envelope or newly developed equatorial flow?

  6. Astrometry of water fountainsMeasurement of absolute coordinates and H2O maser trigonometry SiO masers: W43A with VLA, σ~3 mas (Imai et al. 2005) H2O masers: W43A; IRAS 19134+2131; IRAS 18286-0959; IRAS 18460-0151 with VLBA and VERA, σ~0.2 mas (Imai et al. 2005, 2007, 2013, submitted) 1612 MHz OH masers: W43A; IRAS 18286-0959; IRAS 18460-0151 with VLBA and EVN, σ~2 mas(Imai et al. 2005, 2007, 2013, submitted)

  7. Trigonometric parallax distances Planning water fountain astrometry with VLBA, VERA (after upgrade or KVN+VERA), and LBA including W43A

  8. Large deviation from Galactic rotation Low galactic latitude: suggesting intermediate-mass, old population

  9. Bolometric luminosities of water fountain sources Really intermediate mass AGB/post-AGB stars? van der Veen & Breukers 1989 Nakashima et al. 2000

  10. Thermal molecular emission from water fountains Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope OH H2O CO J=3→2 emission from IRAS 16342-3814 (Imai et al. 2012) See also 12CO and 13CO J=2-1 detections by He et al. (2008) and Rizzo et al. (2011).

  11. SHAPE modelling Steffen et al. 2011 Spherical envelope (+ expanding torus) + collimated jet Gas density ρ(r) Gas clump distribution and relative opacity obtained by Monte-Carlo method simulation Model geometry Vtorus=15 km/s Vjet=550 kms SHAPE model HST image (Sahai et al. 2005)

  12. Extremely low 12C/13C isotopic ratio 12CO 13CO Estimation of possible absolute opacity with RADEX/LAMDA (van der Tak et al. 2007; Schöier et al. 2005) optically thick 12CO, but high intensity ratio cannot be explained 12CO/13CO intensity ratio ~1.5  12C/13C isotopic ratio~1.3 Hot-bottom burning of nucleosynthesis as found in intermediate-mass AGB/post AGB star SHAPE simulation

  13. Relic AGB envelope or new equatorial flow? W43A (1994—2005) Low velocity components (VLSR =9—70 km/s), Vsys (W43A)~35 km/s

  14. Double helix jet model (Yung et al. 2011) IRAS 18286-0959 1612 MHz OH maser Systemic motion Maser motions in 2006—2007 (Imai et al. 2013) Short-lived, low-velocity features Vexp < 30 km/s

  15. Developed relic AGB envelope IRAS 18460-0151 (Imai et al. 2013 submitted) Vexp(OH)~Vexp(H2O low)~20 km/s Dynamical centers within 20 AU ΔVsys=10-40 km/s

  16. Ignition of equatorial flow? IRAS 16342-3814 (Claussen et al. 2009) See also e.g. OH 009.8-0.4 (Walsh et al. 2009) Vsys~40 km/s Vexp(H2O)~ 180 km/s Vexp(OH)~70 km/s

  17. Coevolution of jet and equatorial torus/flow with a time lag • High velocity H2O masers in WFs • Ignition of jet • Maser region comparable to MIR/optical lobes • Low velocity H2O masers in WFs • Shorter ttorus indicating association with relic AGB envelope • Transition from relic envelope to equatorial torus/flow?

  18. Tdyn (maser) < Tdyn (jet) or Tdyn (envelope) Decadal evolution of the W43A H2O masers along the jet (Chong et al. in prep.) Maser region is really evolving. Recurrent maser excitation Some point symmetry But different feature group spacing between blue- and red-shifted lobes

  19. Summary and future perspectives Large deviation of WF sources in the Galactic midplane from Galactic rotation Possible low 12C/13C intensity ratio suggesting the hot-bottom burning nucleosynthesis in an intermediate-mass AGB star Variety of spatio-kinematics of low-velocity H2O maser components: transition from relic AGB envelope to equatorial flow or independent phenomena? Visible decadal evolution/devolution of WF H2O masers L* derived from maser trigonometry in forthcoming VLBI True tdyn of WF jet and envelope/torus measured with ALMA New WF candidates discovered by unbiased maser surveys (H2O: HOPS, OH: SPLASH & GASKAP)

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