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