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 ID: 289288
Download Presentation The PPT/PDF document "Panoramic Views of Water Fountain Source..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Panoramic Views of Water Fountain Sources
Hiroshi ImaiGraduate School of Science and EngineeringKagoshima University
A Neapolitan of Masers: Variability, Magnetism and VLBI
20
May 2013,
CSIRO CASS,
AustraliaSlide2
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)
ⓒ NASA
Betelgeuse (Mira variable) ⓒ NASA
W43A (OH/IR star)
water fountain Deguchi et al. 2007
H
2
O maser
spectrum
(
Likkel
et al. 1992)Slide3
Masers in water fountains
Dynamical centers
within 70 AU
Systemic velocities
w
ithin 3 km/s
H
2O and OH
masers(Imai et al. 2002)SiO and H2O 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)Slide4
Mechanism of stellar jet launch
See Vlemmings’s talk about magnetic fieldMechanism of planetary nebula shaping by jetCharacter of stellar system: single star v.s
. binaryDynamical time scales: t
dyn(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?
Open issues of water fountainsSlide5
Luminosities and
secular motions of the water fountain systemsAstrometry with VLBA and VERAThermal molecular emission (
12CO, 13CO)High velocity molecular component
Hot-bottom burning in nucleosynthesis Kinematics of low velocity H
2
O maser componentsRelic AGB envelope or newly developed equatorial flow?Three new aspects in this talkSlide6
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)
Astrometry of water fountains
Measurement of absolute coordinates and H2O maser trigonometrySlide7
Trigonometric parallax distances
Planning water fountain astrometry with VLBA, VERA(after upgrade or KVN+VERA), and LBA including W43ASlide8
Large deviation from Galactic rotation
Low galactic latitude: suggesting intermediate-mass, old population
IRAS
source
18286-095918460-015119134+2131D [kpc]3.6±0.62.1±0.6
8.0+0.9-0.7R [kpc]
4.8±0.56.3±0.57.4
+0.4-0.3z [pc]7±17±2650+70-60VR [km/s]
51±17100±143+53-46Vθ [km/s]169±22286±16
125+20-28
Vz [km/s]-2±20-9±118+48-39ReferenceImai+2013(in press)Imai+2013(submitted)
Imai+2007Slide9
source
D [kpc]
F12[Jy
](BC
)
12Lbol [Lsun]IRAS 15103-57542.310.864.246800IRAS 16342-3814
2.016.2107.213000
IRAS 18286-09593.6
24.874.8312900W 43A2.623.7315.483900IRAS 18460-01512.1—6.720.902.885490—5000IRAS 18596+0315
1.6?2.59923.28290?IRAS 19134+21318.05.0588.3135000IRAS 19190+11028.61.5904.8311000
Bolometric luminosities of water fountain sources
van der Veen & Breukers 1989Nakashima et al. 2000Really intermediate mass AGB/post-AGB stars?Slide10
H
2
O
OH
CO
J
=3→2 emission from
IRAS
16342-
3814
(Imai et al. 2012)Thermal molecular emission from water fountains
Atacama SubmillimeterTelescope Experiment(ASTE) 10 m telescope
See also 12CO and
13
CO J=2-
1
detections by
He et al. (2008)
and
Rizzo et al. (2011).Slide11
SHAPE
modelling
Spherical envelope (+ expanding torus) + collimated jet
Gas
density
ρ
(r)
Gas clump distribution and relative opacity obtained by Monte-Carlo
method simulation
Steffen et al. 2011HST image(Sahai et al. 2005)
SHAPE
model
Model geometry
V
torus
=15 km/s
V
jet
=550 kmsSlide12
Extremely low
12
C/13C 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 12CO, but high intensity ratio cannot be explained12CO/13CO i
ntensity ratio ~1.5 12C/13
C isotopic ratio~1.3Hot-bottom burning of nucleosynthesis as found in intermediate-mass AGB/post AGB starSlide13
Relic AGB envelope or new equatorial flow?
W43A (1994—2005)
L
ow velocity components (
V
LSR =9—70 km/s), Vsys (W43A)~35 km/sSlide14
IRAS 18286-0959
M
aser motions in 2006—2007
(
Imai et al. 2013)
Short-lived, low-velocity features Vexp < 30 km/s
1612
MHz
OH maserDouble helix jet model(Yung et al. 2011)
SystemicmotionSlide15
V
exp(OH)~Vexp(H2O low)~20 km/s
Dynamical centers within 20 AUΔVsys
=10-40 km/sDeveloped relic AGB envelope
IRAS 18460-0151
(Imai et al. 2013 submitted)Slide16
Ignition of equatorial flow?
V
sys~40 km/s
IRAS 16342-3814(Claussen et al. 2009)
V
exp(H2O)~ 180 km/sVexp(OH)~70 km/sSee also e.g. OH 009.8-0.4 (Walsh et al. 2009) Slide17
Coevolution of jet and equatorial torus/
flow with a time lag
High
velocity H2O masers in WFsIgnition of jet
Maser region
comparable to MIR/optical lobes Low velocity H2O masers in WFsShorter ttorus indicating association
with relic AGB envelopeTransition from relic envelope to equatorial
torus/flow?Slide18
Maser region is really evolving.
Recurrent maser excitationSome point symmetryBut different feature group spacing between blue- and red-shifted lobes
Tdyn
(maser) < Tdyn (jet) or T
dyn
(envelope) Decadal evolution of the W43A H2O masers along the jet(Chong et al. in prep.)Slide19
L
arge deviation of WF sources in the Galactic midplane from Galactic rotation Possible low 12C/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 VLBITrue tdyn of WF jet and envelope/torus measured with ALMANew WF candidates discovered by unbiased maser surveys (H2O: HOPS, OH: SPLASH & GASKAP)Summary and future perspectives