Transcript Hiroshi Imai - 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
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 H 2 O maser spectrum (Likkel et al. 1992) Egg Nebula (post-AGB star)
ⓒ
NASA
Masers in water fountains
H 2 O and OH masers (Imai et al. 2002) SiO and H 2 O masers (Imai et al. 2005) Dynamical centers within 70 AU Systemic velocities within 3 km/s SPITZER/GLIMPSE image around W43A (Deguchi et al. 2007) 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: t dyn (H2O)=l/v exp <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 H 2 O 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 (
12
CO,
13
CO)
High velocity molecular component Hot-bottom burning in nucleosynthesis 3.
Kinematics of low velocity H
2
O maser components
Relic AGB envelope or newly developed equatorial flow?
Astrometry of water fountains
Measurement of absolute coordinates and H 2 O maser trigonometry SiO masers: W43A with VLA, σ~3 mas (Imai et al. 2005) H 2 O 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
D [kpc] R [kpc] z [pc]
V R
[km/s]
V θ
[km/s]
V z
[km/s] Reference
18286-0959
3.6
± 0.6
4.8
± 0.5
7 ± 1 51 ± 17 169 ± 22 -2 ± 20 Imai+2013 (in press)
18460-0151
2.1
± 0.6
6.3
± 0.5
7 ± 2 100 ± 14 286 ± 16 -9 ± 11 Imai+2013 (submitted)
19134+2131
8.0
+0.9
-0.7
7.4
+0.4
-0.3
650 +70 -60 3 +53 -46 125 +20 -28 8 +48 -39 Imai+2007 Low galactic latitude: suggesting intermediate-mass, old population
Bolometric luminosities of water fountain sources
source
IRAS 15103-5754 IRAS 16342-3814
IRAS 18286-0959
W 43A IRAS 18460-0151 IRAS 18596+0315
IRAS 19134+2131
IRAS 19190+1102
D [kpc]
2.3
2.0
3.6
2.6
2.1—6.7
1.6?
8.0
8.6
F
12 [Jy] (BC) 12
10.8 64.24
16.2 107.2
24.87 4.831
23.73 15.48
20.90 2.885
2.599 23.28
5.058 8.313
1.590 4.831
L
bol [L sun ]
6800 13000
2900
3900 490—5000 290?
5000
1000
L
bol Really intermediate mass AGB/post-AGB stars?
( ) 12 = 0.7
+ 2.9
e
7.5
´
C
12 = 1.84
´ ( ) 12 (
F
12 + 0.9
e
1.75
´
C
12 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
H 2 O OH CO J =3→2 emission from IRAS 16342-3814 (Imai et al. 2012)
See also 12 CO and 13 CO J=2-1 detections by He et al. (2008) and Rizzo et al. (2011).
Model geometry
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
SHAPE
model
V
torus =15 km/s
V
jet =550 kms
HST
image (Sahai et al. 2005)
Extremely low 12 C/ 13 C isotopic ratio Estimation of possible absolute opacity with RADEX/LAMDA (van der Tak et al. 2007; Schöier et al. 2005)
optically thick 12 CO, but high intensity ratio cannot be explained
12 CO/ 13
CO intensity ratio ~1.5
12 C/ 13 C isotopic ratio~1.3
Hot-bottom burning of nucleosynthesis as found in intermediate-mass AGB/post AGB star
12 CO 13 CO SHAPE simulation
Relic AGB envelope or new equatorial flow?
W43A (1994 — 2005) Low velocity components (V LSR =9 — 70 km/s), V sys (W43A)~35 km/s
Double helix jet model (Yung et al. 2011) Systemic motion IRAS 18286-0959 Maser motions in 2006 —2007 (Imai et al. 2013) 1612 MHz OH maser Short-lived, low-velocity features
V
exp < 30 km/s
Developed relic AGB envelope
V
exp (OH)~V exp (H 2 O low)~20 km/s Dynamical centers within 20 AU Δ
V
sys =10-40 km/s IRAS 18460-0151 (Imai et al. 2013 submitted)
Ignition of equatorial flow?
IRAS 16342-3814 (Claussen et al. 2009)
See also e.g. OH 009.8-0.4 (Walsh et al. 2009)
V
exp (H 2 O)~ 180 km/s
V
exp (OH)~70 km/s
V
sys ~40 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 t torus indicating association with relic AGB envelope Transition from relic envelope to equatorial torus/flow?
T
dyn (maser) < T dyn or T dyn (jet) (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 H 2 O 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 12 C/ 13 C 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 t dyn of WF jet and envelope/torus measured with ALMA New WF candidates discovered by unbiased maser surveys (H2O: HOPS, OH: SPLASH & GASKAP)