astrometry of water masers in post-agb stars
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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 - PowerPoint PPT PresentationTRANSCRIPT
Astrometry of Water Masers in Post-AGB Stars
Hiroshi ImaiGraduate School of Science and Engineering, Kagoshima
University
ContentsAstrometry 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.
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 resolution10-100 micro-arcseconds level astrometric accuracyradio astrometry for non-thermal sources, e.g. maserstrigonometric parallax measurement on kpc-scaleabsolute 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 0.3-2.2 deg.
measurement of atmospheric zenith delay residual using GPS data
Tracking motions of water maser features
Galacticrotation
Water masers in IRAS 19134+2131 (Imai et al. 2007)
Detection of annual parallax
Maser spot motion in IRAS 22480+6002 (Preliminary) π=~360 μas, D~2.8 kpc
Target sources and scientific goals
water fountains (AGB/post-AGB)IRAS 19134+2131IRAS 18286-0959
pre-planetary nebulaIRAS 19312+1950
planetary nebulaK3-35
K-type supergiantIRAS 22480+6002
trigonometric parallax distancessource luminositysource mass
secular motiondeviation from
circular Galactic rotation
birth point and ageInternal motion of
water maser sourcekinematic property
of bipolar jet, equatorial torus, and circumstellar envelope
IRAS 19134+2131 (water fountain)
Dynamical age of jet ~50 yearsWatching light from
central star
Imai, Sahai, & Morris (2007)
IRAS 19134+2131 (water fountain)
Travel time from the Galactic plane
1.1-7.7 x 107 yearsStellar mass M*< 5-5.8 M◉
Imai, Sahai, & Morris (2007)
IRAS 18286-0959 (water fountain, double helix)
Discovered in SPIZER/GLIMPS image
(Deguchi et al. 2007)
Dynamical age of jet ~60 yearsDiscontinuous 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 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)
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 19312+1950(pre-planetary nebula)
Double peaks (ΔV~30 km/s) of H2O and SiO masersSmall relative proper
motionsBinary system?
or bipolar flow?
Enigmatic sourceC-rich/O-rich hybrid
chemistry in envelope
Nakashima et al. (2011)
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~10-4 Msun 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 yearsDynamical time scale of
the bipolar nebula ~1000 years
Tafoya et al. (2011)
Miranda et al. (2001)
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)
IRAS 22480+6002 (K-type star)
First example of H2O maser source associated with K-type starBipolar flow traced by H2O maser motions
(Imai et al. 2008; Imai et al. in prep.)
2MASS image
IRAS 22480+6002
D=2.8+0.37-0.29 kpc
(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
Preliminaryresults
Future perspectives
Upgrade in VLBA and VERAWider 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 nebulaeEvolved stars with peculiar motionsDiagnostics of luminosities, masses, mass loss rates,
binarity, etc. to track the final stellar evolution Larger sample: GBT, Effelsberg, EVLA /ALMA
…..ASKAP/SKAOH masers in the Galactic disk, bulge, and haloKinematic study on maser sources in the Magellanic
Clouds