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 K3-35 IRAS IRAS IRAS Future perspectives This talk is based on several researches with collaborators listed as follows. Guillem Anglada, Philip J. Diamond, Shuji Deguchi, Yolanda Gómez, Tomoya Hirota, Mareki Honma, Murray B. Lewis, Sun Kwok, Luis F. Miranda, Takeshi Miyaji, Mark Morris, Hiroyuki Nakanishi, Jun-ichi Nakashima, Nimesh Patel, Raghvendra Sahai, Daniel Tafoya, Jose, M. Torrelles, Bosco Yung, and VERA collaboration

Astrometry with VLBA and VERA (Sub) milli-arcsecond level angular resolution 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

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

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

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

Target sources and scientific goals water fountains (AGB/post-AGB) IRAS IRAS pre-planetary nebula IRAS planetary nebula K3-35 K-type supergiant IRAS 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

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

IRAS (water fountain) Travel time from the Galactic plane x 10 7 years Stellar mass M * < M Imai, Sahai, & Morris (2007)

IRAS (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.) Yung et al. (2011) Location of 1612 MHz OH maser (Imai et al. 2008)

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

IRAS (pre-planetary nebula) Double peaks (ΔV~30 km/s) of H 2 O 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)

IRAS D= kpc (R,z)= (7.1±0.1 kpc, 28±3 pc) (V R, V θ, V z ) [km s -1 ]= (33±28, 214±4, -14±8) L * ~18,000 L sun dM/dt~10 -4 M sun yr -1 Roughly following circular Galactic rotation, but it is not a YSO. Imai et al. (2011)

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

K3-35 (planetary nebula) D= kpc (R,z) [kpc, pc]= (7.1±0.1, ) (V R, V θ, V z ) [km s -1 ]= (33±16, 233±11, 11±2) Following circular Galactic rotation Tafoya et al. (2011)

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

IRAS D= kpc (R,z)=(9.7±0.2 kpc, 59±6 pc) (V R, V θ, V z ) [km s -1 ]= (203±6, 54±4, -3±1) L * ~45,000 L sun K-type supergiant harboring H 2 O/SiO maser emission Preliminary results

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