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Astrometry of Water Masers in Post-AGB Stars

Astrometry of Water Masers in Post-AGB Stars. Hiroshi Imai Graduate School of Science and Engineering, Kagoshima University. Contents. Astrometry with VLBA , and VERA (EVN for OH masers) Results of astrometry IRAS 19134+2131 K3-35 IRAS 19312+1950 IRAS 18286-0959 IRAS 22480+6002

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Astrometry of Water Masers in Post-AGB Stars

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  1. Astrometry of Water Masers in Post-AGB Stars Hiroshi Imai Graduate School of Science and Engineering, Kagoshima University

  2. Contents • Astrometry with VLBA, and VERA (EVN for OH masers) • Results of astrometry • IRAS 19134+2131 • K3-35 • IRAS 19312+1950 • IRAS 18286-0959 • IRAS 22480+6002 • Future perspectives This talk is based on several researches with collaborators listed as follows. GuillemAnglada, Philip J. Diamond, ShujiDeguchi, Yolanda Gómez, TomoyaHirota, MarekiHonma, Murray B. Lewis, Sun Kwok, Luis F. Miranda, Takeshi Miyaji, Mark Morris, Hiroyuki Nakanishi, Jun-ichiNakashima, Nimesh Patel, RaghvendraSahai, Daniel Tafoya, Jose, M. Torrelles, Bosco Yung, and VERA collaboration

  3. Astrometry with VLBA and VERA • (Sub) milli-arcsecondlevel angular resolution • 10-100 micro-arcseconds level astrometric accuracy • radio astrometry for non-thermal sources, e.g. masers • trigonometric parallax measurement on kpc-scale • absolute coordinates and secular motions

  4. Dual beam system equipped for VERA • perfect compensation of atmospheric fluctuation and instrumental delay difference between position-reference and target sources separated by 0.3-2.2 deg. • measurement of atmospheric zenith delay residual using GPS data

  5. Tracking motions of water maser features Galactic rotation Water masers in IRAS 19134+2131 (Imai et al. 2007)

  6. Detection of annual parallax Maser spot motion in IRAS 22480+6002 (Preliminary) π=~360μas, D~2.8 kpc

  7. Target sources and scientific goals • trigonometric parallax distances • source luminosity • source mass • secular motion • deviation from circular Galactic rotation • birth point and age • Internal motion of water maser source • kinematic property of bipolar jet, equatorial torus, and circumstellar envelope • water fountains (AGB/post-AGB) • IRAS 19134+2131 • IRAS 18286-0959 • pre-planetary nebula • IRAS 19312+1950 • planetary nebula • K3-35 • K-type supergiant • IRAS 22480+6002

  8. IRAS 19134+2131 (water fountain) Dynamical age of jet ~50 years Watching light from central star Imai, Sahai, & Morris (2007)

  9. IRAS 19134+2131 (water fountain) • Travel time from the Galactic plane • 1.1-7.7 x 107years • Stellar mass • M*< 5-5.8 M◉ Imai, Sahai, & Morris (2007)

  10. IRAS 18286-0959 (water fountain, double helix) Discovered in SPIZER/GLIMPS image (Deguchi et al. 2007) Dynamical age of jet ~60 years Discontinuous mass ejection to form the double helix (Jet 1 is younger than Jet 2.) Location of 1612 MHz OH maser (Imai et al. 2008) Yung et al. (2011)

  11. IRAS 18286-0959 D=3.9+1.1-0.7 kpc (R,z)=(4.9±0.7 kpc, 22±2 pc) (VR, Vθ, Vz) [km s-1]= (64±30, 133±36, -17±31) • Motions of spots in Jet 2: • large deviation from • circular Galactic rotation • consistent with jet motion (~100 km/s) + stellar motion (~30 km/s)? Preliminary results (will be revised) Imai et al. (in prep.)

  12. IRAS 19312+1950(pre-planetary nebula) • Double peaks (ΔV~30 km/s) of H2O and SiO masers • Small relative proper motions • Binary system? or bipolar flow? • Enigmatic source • C-rich/O-rich hybrid chemistry in envelope Nakashima et al. (2011)

  13. IRAS 19312+1950 D=3.8+0.8-0.6 kpc (R,z)= (7.1±0.1 kpc, 28±3 pc) (VR, Vθ, Vz) [km s-1]= (33±28, 214±4, -14±8) L*~18,000 Lsun dM/dt~10-4Msun yr-1 Roughly following circular Galactic rotation, but it is not a YSO. Imai et al. (2011)

  14. K3-35 (planetary nebula) • Photo ionization time scale ~50 years • Dynamical time scale of the bipolar nebula ~1000 years Miranda et al. (2001) Tafoya et al. (2011)

  15. K3-35 (planetary nebula) D=3.9+0.7-0.5 kpc (R,z) [kpc, pc]= (7.1±0.1, 140+25-18) (VR, Vθ, Vz) [km s-1]= (33±16, 233±11, 11±2) Following circular Galactic rotation Tafoya et al. (2011)

  16. IRAS 22480+6002 (K-type star) 2MASS image First example of H2O maser source associated with K-type star Bipolar flow traced by H2O maser motions (Imai et al. 2008; Imai et al. in prep.)

  17. IRAS 22480+6002 D=2.8+0.37-0.29kpc (R,z)=(9.7±0.2 kpc, 59±6 pc) (VR, Vθ, Vz) [km s-1]= (203±6, 54±4, -3±1) L*~45,000 Lsun K-type supergiant harboring H2O/SiO maser emission Preliminary results

  18. Future perspectives • Upgrade in VLBA and VERA • Wider receiving band width for detecting fainter position-reference sources closer to target stars. • Higher dispersion spectroscopy for water fountains. • Joint operation of VERA and KVN • Statistical analysis of astrometric information • ~15 water fountain sources • ~10 pre-planetary and planetary nebulae • Evolved stars with peculiar motions • Diagnostics of luminosities, masses, mass loss rates, binarity, etc. to track the final stellar evolution • Larger sample: GBT, Effelsberg, EVLA /ALMA …..ASKAP/SKA • OH masers in the Galactic disk, bulge, and halo • Kinematic study on maser sources in the Magellanic Clouds

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