a birth and growth of a collimated molecular jet from an agb star
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Future Directions in High Resolution Astronomy: A Celebration of the 10th Anniversary of the VLBA. A Birth and Growth of a Collimated Molecular Jet from an AGB Star. Hiroshi Imai (Joint Institute for VLBI in Europe, NL) Philip J. Diamond (Jodrell Bank Observatory, UK). - PowerPoint PPT PresentationTRANSCRIPT
A Birth and Growth of a Collimated Molecular Jet from an AGB Star
Hiroshi Imai (Joint Institute for VLBI in Europe, NL)
Philip J. Diamond(Jodrell Bank Observatory, UK)
Future Directions in High Resolution Astronomy: A Celebration of the 10th Anniversary of the VLBA
• Water fountains: cites of stellar jet’s birth• W43A: an AGB star having a jet and an envelope • Implication of the W43A jet
The Great Barrier Dam, the Netherlands
Jet formation in final stellar evolution
• Central objects of planetary nebulae (PNe) = post-AGB stars
– Bipolar jets (>100 km/s, >> 1000K, ionized)– Producing complicated PN morphology
Jet from a planetary nebula: Henize 2-90 (Sahai & Nyman 2000)
Jet formation in final stellar evolution
When such stellar jets are launched ?
How to launch such stellar jets ?
Jet from a planetary nebula: Henize 2-90 (Sahai & Nyman 2000)
High velocity stellar molecular flows
• Before finding optical jet • Dragged by a (unseen) collimated jet
Outflow in OH 231.8+4.2 (Alcolea et al. 2001)
Jet Outflow
High velocity stellar molecular flows
What is the central star?
White dwarf ? Mira star ?
or young star ?
Outflow in OH 231.8+4.2 (Alcolea et al. 2001)
Transition from AGB to post-AGB
Spherical circumstellar envelope: around RT Virginis (Imai et al. 2003, see poster no .62
• A Mira variable (AGB star):
– Pulsation– Spherical
envelope– Small bipolarity– Slow wind
(~10 km/s)
Transition from AGB to post-AGB
A Mira-star envelope is transformed to a collimated jet smoothly ?
Spherical circumstellar envelope: around RT Virginis (Imai et al. 2003, see poster no .62
High velocity H2O maser sources (Likkel et al. 1992)
Water fountains: cites of on-going jet formation
• V(H2O) >= 100 km/s >> V(OH) =< 30 km/s
• Clear double peaks• Symmetric with respect to
the systemic velocity
W43A
IRAS16342-3814
IRAS19134+2131
High velocity H2O maser sources (Likkel et al. 1992)
Water fountains: cites of on-going jet formation
• Newly-formed jets or extreme super winds ?
• How old ?
• How to produce ?
• Young stellar objects ?
W43A
IRAS16342-3814
IRAS19134+2131
VLBA observations of the W43A H2O/OH masers
• H2O masers: Jun. 1994, Oct. 1994, Mar. 1995,
Apr. 2002, Jul. 2002, Nov. 2002, Apr. 2003, ..... (now going on)
Synthesized beam: ~0.5 masVelocity resolution: 0.2 km/s
• OH masers (1612, 1665 & 1667MHz): Jun. 1994, Oct. 1994, Mar. 1995, Dec. 2001, Aug. 2002, ..... (now going on) Synthesized beam: ~9 mas
Velocity resolution: 0.45 km/s
History of the W43A jet
1970 1980 1990 2000 2010 2020 2030....
Birth of the molecular jet (at my birthday?)
Discovery of the high-velocity masers (Genzel & Downes 1977)
H2O maser observations(7 epochs)
OH maser observations(5 epochs)
Destruction of the molecular jet (at the end of my life?)
Discovery of the molecular jet (Imai et al. 2002)VLBA operation
(Since 1993)
Highly-collimated jet of molecular gas
The first one year: Imai, Obara, Diamond, Omodaka, & Sasao 2002
Jet parameters (1994 - 1995)
-300
-200
-100
0
100
-700-600-500-400-300-200-1000100
119 - 126 km/s114 - 117 km/s-3 - 0 km/s-8 - -7 km/s-50 - -46 km/s-57 - -50 km/s
Dec
l. o
ffse
t (m
as)
R.A. offset (mas)
Proper motion100 km/s
• 3D jet speed: 145 +/-20 km/s in major axis • Standard deviation ratio:
V(jet)/V(internal) = 9.5 +/-4.1 (variance-covariance analysis)
21 proper motions
Imai et al. (2002)
Jet parameters (1994 - 1995)
-300
-200
-100
0
100
-700-600-500-400-300-200-1000100
119 - 126 km/s114 - 117 km/s-3 - 0 km/s-8 - -7 km/s-50 - -46 km/s-57 - -50 km/s
Dec
l. o
ffse
t (m
as)
R.A. offset (mas)
Proper motion100 km/s
• Jet alignment: length = 1700 AU, P.A.= 69.3±0.3 deg.• Cluster alignment: length = 250, 350 AU, width < 30 AU
P.A.= 54.6+/-6.0 deg., 57.2+/-0.3 deg. (red, blue clusters)
21 proper motions
Imai et al. (2002)
H2O maser kinematics in 2002Imai & Diamond (2003)
Growth of the molecular jet• Growth rate of jet ~ 300AU/ 8 years ~ 180 km/s• Birth of the jet around the year 1970
Point symmetry
Constant-velocity motion of each
maser cloud
Interaction with the ambient envelope
A precessing jet model
Straight alignments with axis offsets
>>> lifetime of maser clouds ~ 10 years
A precessing jet model
The W43A jet is precessing !
-500
-250
0
250
500
-1000-50005001000
Maser spot (Oct. 1994)Precessing jet model (1994.8)
Y (
AU
)
X (AU)
Period ~ 55 years Amplitude ~ 5 degrees Inclination ~ 39 degrees
The precession is true !
-500
-250
0
250
500
-1000-50005001000
Maser spot (Oct. 1994)Precessing jet model (1994.8)
Y (
AU
)
X (AU)
Maser spot (Apr. 2002)Precessing jet model (2002.3)
A consistent model at every epoch >>> direct estimation: d (~2.6 kpc),
origin location, and jet ignition time (~30 yr ago)
What star is W43A ?
An AGB star!
Periodic flux variation (P~ 400 d) in OH 1612 MHz masers(Harman & Habing 1985; van Langevelde et al. 1990)
Dwingeloo 25-m telescope
Signatures of an pulsating star
-300
-200
-100
0
100
-700-600-500-400-300-200-1000100
1994 October 10
118 - 126 km/s114 - 118 km/s-8 - 0 km/s-51 - -46 km/s-57 - -51 km/s
Dec
l. of
fset
(m
as)
R.A. offset (mas)
500 AU @2.6 kpc
Spherically-expanding envelope• The same systemic velocity of
the H2O and OH masers (VLSR ~ 34 km/s)• Similar to Mira OH maser sources
OH masers
-150
-100
-50
0
50
100
150
050100150200250300
1994 June-October
42 - 44 km/s38 - 42 km/s25 - 30 km/s
Dec
l. of
fset
(m
as)
R.A. offset (mas) 1612 MHz OH masers
Spherically-expanding envelope• The same systemic velocity of
the H2O and OH masers (VLSR ~ 34 km/s)
• Dynamical time scale of the envelope ~ 260 years
OH masers
-150
-100
-50
0
50
100
150
050100150200250300
1994 June-October
42 - 44 km/s38 - 42 km/s25 - 30 km/s
Dec
l. of
fset
(m
as)
R.A. offset (mas) Distance - velocity diagram
• Mira stars:– Elongation of
circumstellar envelop(Elitzur et al. 2003)
– by jets ? or by others?
• OH/IR stars: – Super winds (~1000 years)
– H2O maser jets: < 100 years
– Later outflows, optical jets
– H2O maser segments in PPNs
When is a stellar jet launched? H2O masers and a jet in PPN
(Miranda et al. 2001)
Morphology of planetary nebulae
Determined by
the envelope morphology
at AGB phase,
created by a stellar jet !
Water fountains = Molecular jets
UH88+Sirius image (Deguchi & Nakashima 2002)
Imai, & Diamond 2003
W43A
IRAS16342-3814
IRAS19134+2131
Water fountains = Molecular jets
HST image (Sahai et al. 1999)
Morris, Sahai & Claussen 2003
W43A
IRAS16342-3814
IRAS19134+2131
Water fountains = Molecular jets
2MASS All Sky Survey image
Imai, Morris & Sahai 2003
W43A
IRAS16342-3814
IRAS19134+2131
3-D jet speed: ~120 km/sDynamical time scale ~ 90 years
Water fountains = Molecular jetsW43A
IRAS16342-3814
IRAS19134+2131
Similar sizes (2000 - 4000 AU)
and dynamical time scales
(< 100 years) of the molecular jets !
Duration of molecular jetin the earliest phase of stellar jets: ~ 100 years
A molecular jet in W43A
was born with me and
will disappear with me!
A sensational chance in my life!
The Prince Charles, visiting in the MERLIN upgrade celebrationon 28 April 2003 at Jodrell Bank Observatory, UK
Schematic cartoon of W43A
Kasteel de Haar, the Netherlands
Thank you !
Circumstellar envelope of W43A
+H2O & OH masers
2.7 mm dust continuum emission (NMA observation)(Imai et al. 2003)
20000 AU at 2.6 kpc
Well developed, but compact ......
•Size < 10000 AU •Mass ~ 15 Msun
(including foreground cloud)• Optically thin (spectral index~3-4)
Circumstellar envelope of W43A Has not be ionized yet .....
+H2O & OH masers
20000 AU at 2.6 kpc
UH88+Sirius JHK-band image (Deguchi & Nakashima 2002)
Signatures of going mass loss
SiO maser emission(see Nakashima & Deguchi 2003)
Rotating disk ?
e.g.IRC -10414
(Imai et al. 1999)NML Cyg (Boboltz & Marvel 1999)OH 231.8+4.2 (Sanchez Contreras et al.
2002)