water as tracer of the stormy stages of star formation · 2010. 12. 14. · stormy stages of star...
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Water as tracer of the stormy stages of star
formation
Lars E. KristensenE.F. van Dishoeck, R. Visser, U.A. Yildiz, G.J. Herczeg,
J.K. Jørgensen, M.R. Hogerheijde, C. Brinch, S.D. Doty, T.A. van Kempen, S.F. Wampfler, S. Bruderer, A.O. Benz,
and the WISH team
WISHWhat ?- Water In Star-forming regions with Herschel- HIFI Guaranteed time key programme, PI: E.F. van Dishoeck (Leiden Observatory, NL)- 425h being observed (HIFI and PACS)
Goal:- Use H2O to trace physical and chemical conditions- Complementary to CO
Why H2O ?- Dynamical probe: outflow, infall, quiescent...- Main reservoir of O, tracing gas-grain interactions- Important for life on Earth
15 first-results papers + van Dishoeck et al. (PASP, subm.)
A.Karska
etal.2010:APEX
CHAMP+high-JCO
observationsofL1527and
L4837
Fig.4.Toppanel:CO
6-5and
CO7-6
mapsofL1527.Contourlevelsare6!
,12!,18!
etc.(!(CO
6!5)=1.5
Kand!(CO
7!6)=4.1
K).Centralposition
ismarked
withaX.Bottom
panel:SpectralmapsofL1527
inCO
6-5(right)and
CO7-6
(left)transitions.
Time
Mass
Prestellar
Class 0
Class 1
Disks
Intermediate- High-massLow-
~80 sources~80 sources
Observations
Kristensen et al. (2010)
NGC1333
Nearby low-mass star-forming region
D ~ 235 pcL ~ 6-20 L⊙◉☉⨀
Observations
Kristensen et al. (2010)
NGC1333
Nearby low-mass star-forming region
D ~ 235 pcL ~ 6-20 L⊙◉☉⨀
Energetic inputPassively
heated molecular envelope
UV-illuminated cavity walls
Small-scale shocks in
cavity walls
Molecular jet, internal working surfaces
(Visser, Kristensen et al. in prep.)
Passively heated
molecular envelope
UV-illuminated cavity walls
Small-scale shocks in
cavity walls
Molecular jet, internal working surfaces
Energetic input
Physical conditions:• nH ~ 104 - 108 cm-3
• T ~ 10 - 2000 K• B ~ 10-3 - 1 mGauss• G0 ~ 1 - 104
• v ~ 0 - 100 km s-1
(Visser, Kristensen et al. in prep.)
First Herschel H2O map
Spitzer IRAC
Herschel PACS
(Nisini et al. 2010)
L1157L ~ 6 L⊙◉☉⨀
D ~ 325 pc
HH46
200 0 200 0
50
100
150Fl
ux d
ensi
ty [J
y]
200 0 200 0
50
100
150Fl
ux d
ensi
ty [J
y][O I]
84.4 84.6
84.4 84.6
x3
x10
x3OH
[µm] 200 0 200
200 0 200
x5
x40
x10
Velocity [km s 1]
H2O
250 0 250
250 0 250
x10
x10
x10CO
Kristensen et al. in prep.; van Kempen, Kristensen et al. (2010)
HH46L ~ 12 L⊙◉☉⨀D ~ 450 pc
CO 16-15H2O 110-101 @ 557 GHz
Δv ~ 35 km/s
HIFI
Modelling strategyStep 1:Split YSO into different components
Step 2:Model each component using state-of-the-art models
Status:Working for CO ( Yildiz et al. 2010, Visser et al. in prep.)
Goal:Do this for H2O
0 10 20 30 40J
u
10-19
10-18
10-17
10-16
10-15
Flux
[W m
-2]
Passive
C-shocks
UV
Total
CO
0 10 20 30 40J
u
10-19
10-18
10-17
10-16
10-15
Flux
[W m
-2]
10 100 500 1000 2000 3000 4000E
u / k
B [K]
Decomposing CO
Seen in all YSOs!
van Kempen, Kristensen et al. (2010)
• Three mechanisms:
• Passively heated envelope
• UV-heated cavity walls
• Shocks
• Free parameters:
• UV-luminosity (0.1-1.0 L⊙◉☉⨀)
• vshock (20 km/s)
H2O profile safari
Kristensen et al. (2010);
Kristensen et al. in prep.
HIFI observations
of H2O 110-101 at 557
GHz
If it moves, it emits H2O!
Bullets
EnvelopeAbsorption
belowcontinuum
InverseP-Cygni
Absorption
Class 0 Class 0
Class I H218O
H2O abundance
H2O/CO ~ 1-10, i.e., x(H2O) ~ 10-5 - 10-4
Consistent with, e.g., Orion (Franklin et al. 2008)
Fraction of outflow gas where O + H2 -> H2O:
~ 10%
TM
B (K)
CO
6-5 / H2 O
202 -1
11
x(H
2O)
1.5e-5
8e-6
6e-6
4e-6
6e-5
Take-home messages
• H2O:
• Detected in all (low-mass) YSOs
• If it moves, it emits water
• x(H2O) increases with velocity in shocks
• Quiescent abundance is low
• Modelling:
• 3-component model (passive+UV+shocks) works
PAC
S
Origin of H2O emission
Spitzer: hot H2O(Watson et al. 2007)
Origin: disk, shocks, other ?
HIFI: shocks
H218O at 203 GHz: disk(Jørgensen & van Dishoeck
2010)
NGC1333-IRAS4B
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