Hiroshi Imai - Panoramic Views Of Water Fountain Sources

Report
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
Water fountain
highly 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
Masers in water fountains
H2O and OH masers
(Imai et al. 2002)
SiO and H2O masers
SPITZER/GLIMPSE
image around W43A
(Deguchi et al. 2007)
(Imai et al. 2005)
Dynamical centers
within 70 AU
Systemic velocities
within 3 km/s
VLT 11.85
micron image of W43A
(Lagadec et al. 2011)
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?
Three new aspects in this talk
1. Luminosities and secular motions of the
water fountain systems
 Astrometry with VLBA and VERA
2. Thermal molecular emission (12CO, 13CO)
 High velocity molecular component
 Hot-bottom burning in nucleosynthesis
3. Kinematics of low velocity H2O maser
components
 Relic AGB envelope or newly developed
equatorial flow?
Astrometry of water fountains
Measurement 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)
Trigonometric parallax distances
Planning water fountain astrometry with VLBA, VERA
(after upgrade or KVN+VERA), and LBA including W43A
Large deviation from Galactic rotation
IRAS source
18286-0959
18460-0151
19134+2131
D [kpc]
3.6±0.6
2.1±0.6
8.0+0.9-0.7
R [kpc]
4.8±0.5
6.3±0.5
7.4+0.4-0.3
z [pc]
7±1
7±2
650+70-60
VR [km/s]
51±17
100±14
3+53-46
Vθ [km/s]
169±22
286±16
125+20-28
Vz [km/s]
-2±20
-9±11
8+48-39
Reference
Imai+2013
Imai+2013
(submitted)
Imai+2007
(in press)
Low galactic latitude: suggesting intermediate-mass, old
population
Bolometric luminosities of water fountain sources
source
D [kpc]
F12[Jy] (BC)12
Lbol [Lsun]
IRAS 15103-5754
2.3
10.8 64.24
6800
IRAS 16342-3814
2.0
16.2 107.2
13000
IRAS 18286-0959
3.6
24.87 4.831
2900
W 43A
2.6
23.73 15.48
3900
IRAS 18460-0151
2.1—6.7
20.90 2.885
490—5000
IRAS 18596+0315
1.6?
2.599 23.28
290?
IRAS 19134+2131
8.0
5.058 8.313
5000
IRAS 19190+1102
8.6
1.590 4.831
1000
Really intermediate mass AGB/post-AGB stars?
-7.5´C12
1.75´C12
BC
=
0.7
+
2.9e
+
0.9e
( )12
Lbol [ Lsun ] =1.84 ´ ( BC )12 ( F12 1Jy) ( D 1kpc)
2
van der Veen & Breukers 1989
Nakashima et al. 2000
Thermal molecular emission from water fountains
Atacama Submillimeter
Telescope Experiment
(ASTE) 10 m telescope
H2 O
OH
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).
SHAPE modelling
Steffen et al. 2011
Spherical envelope (+ expanding torus)
+ collimated jet
Gas density ρ(r)
Model geometry Gas clump distribution and relative
opacity obtained by Monte-Carlo
method simulation
SHAPE model
HST image
(Sahai et al. 2005)
Vtorus=15 km/s
Vjet=550 kms
Extremely low 12C/13C isotopic ratio
 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
12CO
intermediate-mass AGB/post AGB star
13CO
SHAPE simulation
Relic AGB envelope or new equatorial flow?
W43A (1994—2005)
Low velocity components (VLSR =9—70 km/s), Vsys (W43A)~35 km/s
Double helix jet model
(Yung et al. 2011)
IRAS 18286-0959
Maser motions in 2006—2007
(Imai et al. 2013)
Systemic
motion
1612 MHz
OH maser
Short-lived, low-velocity features
Vexp < 30 km/s
Developed relic AGB envelope
 Vexp(OH)~Vexp(H2O low)~20 km/s
 Dynamical centers within 20 AU
 ΔVsys=10-40 km/s
IRAS 18460-0151
(Imai et al. 2013 submitted)
Ignition of equatorial flow?
IRAS 16342-3814
(Claussen et al. 2009)
Vsys~40 km/s
See also e.g. OH 009.8-0.4
(Walsh et al. 2009)
 Vexp(H2O)~ 180 km/s
 Vexp(OH)~70 km/s
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?
Tdyn (maser) < Tdyn (jet)
or Tdyn (envelope)
 Maser region is really
evolving.
 Recurrent maser excitation
 Some point symmetry
 But different feature
group spacing between
blue- and red-shifted lobes
Decadal evolution of the W43A
H2O masers along the jet
(Chong et al. in prep.)
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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