Hiroshi Imai - Panoramic Views Of Water Fountain Sources

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Nov 14, 2013 (3 years and 11 months ago)

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Panoramic Views of Water Fountain Sources

Hiroshi Imai


Graduate School of Science and Engineering

Kagoshima University

A Neapolitan of Masers: Variability, Magnetism and VLBI

20
May 2013,
CSIRO CASS,
Australia

Water fountain

highly collimated, fast, stellar, molecular jet

from
AGB to post
-
AGB
star,

from
spherical symmetric to

asymmetric
circumstellar envelope

Egg Nebula

(post
-
AGB star)


乁十

Betelgeuse

(
Mira variable
)



NASA

W43A (OH/IR star)

water fountain


Deguchi et al. 2007

H
2
O maser

spectrum

(
Likkel

et al. 1992)

Masers in water fountains

Dynamical centers

within 70 AU

Systemic velocities

w
ithin 3 km/s

H
2
O and
OH
masers

(
Imai et al. 2002
)

SiO and H
2
O masers

(Imai et al. 2005)

SPITZER/GLIMPSE

image around W43A

(
Deguchi et al.
2007)

VLT 11.85

micron image of W43A

(
Lagadec

et al. 2011)


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,

B
ut equal to true ages? Can we see evolution/devolution?


Precessing jets? Recurrent jet ignitions?


Main
-
sequence
m
ass and evolutionary phase of host star?


What is low
-
velocity H
2
O maser components?

Open issues of water fountains

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?

Three new aspects in this talk


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)


Astrometry of water fountains


Measurement of absolute coordinates and

H
2
O maser trigonometry

Trigonometric parallax distances

Planning water fountain astrometry with VLBA, VERA

(after upgrade or KVN+VERA), and LBA including W43A

Large deviation from Galactic rotation

Low
g
alactic latitude: suggesting intermediate
-
mass, old
population

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

V
R
[km/s]


51
±
17

100
±
14

3
+53
-
46

V
θ

[km/s]

169
±
22

286
±
16

125
+20
-
28

V
z

[km/s]


-
2
±
20

-
9
±
11

8
+48
-
39

Reference

Imai
+20
13

(in press)

Imai+2013

(submitted)

Imai+2007

source

D

[kpc]

F
12
[
Jy
]

(
BC
)
12

L
bol

[
L
sun
]

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

Bolometric luminosities of water fountain sources

B
C


1
2

0
.
7

2
.
9
e

7
.
5

C
1
2

0
.
9
e
1
.
7
5

C
1
2
L
b
o
l
L
s
u
n



1
.
8
4

B
C


1
2
F
1
2
1
J
y


D
1
k
p
c


2
v
an der
Veen

&
Breukers

1989

Nakashima et al. 2000

Really intermediate mass AGB/post
-
AGB stars?

H
2
O

OH

CO
J
=3→2 emission from

IRAS
16342
-
3814

(Imai et al. 2012)

Thermal molecular emission from water fountains

Atacama Submillimeter

Telescope Experiment

(ASTE) 10 m telescope

See also
12
CO and
13
CO J=2
-
1

detections by

He et al. (2008) and Rizzo et al. (2011).

SHAPE

modelling

Spherical envelope (+ expanding torus)
+ collimated jet

Gas
density
ρ
(r)

Gas
clump distribution and
relative

opacity obtained by
Monte
-
Carlo
method simulation

Ste

敮e整e慬⸠
㈰21

HST

image

(Sahai et al. 2005)


SHAPE

model

Model geometry

V
torus
=15 km/s

V
jet
=550 kms

Extremely low
12
C/
13
C isotopic ratio

12
CO





13
CO

SHAPE
simulation


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
i
ntensity 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


Relic AGB envelope or new equatorial flow?

W43A (1994

2005)

L
ow velocity components (
V
LSR

=9

70 km/s),
V
sys

(W43A)~35 km/s

IRAS 18286
-
0959

M
aser motions in 2006

2007



(
Imai et al. 2013)




Short
-
lived, low
-
velocity features


V
exp

< 30 km/s

1612
MHz

OH maser

Double helix jet model

(Yung et al. 2011)

Systemic

motion


V
exp
(OH)~
V
exp
(H
2
O low)~20 km/s


Dynamical centers within 20 AU


Δ
V
sys
=10
-
40 km/s

Developed relic AGB envelope

IRAS 18460
-
0151


(Imai et al. 2013 submitted)

Ignition of equatorial flow?

V
sys
~40 km/s

IRAS 16342
-
3814

(Claussen et al. 2009)


V
exp
(H
2
O)~ 180 km/s


V
exp
(OH)~70 km/s

See also e.g. OH 009.8
-
0.4

(Walsh et al. 2009)

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?


Maser region is really
evolving.


Recurrent maser excitation


Some point symmetry


But different feature
group spacing between
blue
-

and red
-
shifted lobes

T
dyn

(maser) <
T
dyn

(jet)
or
T
dyn

(envelope)

Decadal evolution of the W43A
H
2
O masers along the jet

(Chong et al. in prep.)


L
arge deviation of WF sources in the Galactic midplane from
Galactic rotation


Possible low
12
C/
13
C intensity ratio suggesting the hot
-
bottom
b
urning 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
m
aser 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)

Summary and future perspectives