Eidgenössische Technische Hochschule Zürich

Swiss Federal Institute of Technology, Zürich

Water Key ProgramHerschel/HIFI

Hydrides

Pascal StäuberEwine van Dishoeck

Jes JørgensenSteven DotyArnold Benz

Why Observe Hydrides?

1. Part of water network (OH+)

2. Interesting also for other networks (CH2, H2S)

3. Tracers for FUV and X-ray emissions

4. New molecules, not observable from ground

H2OH3O+ OH

H2O+ OH+ O+

O2

OH2

H2

H2

H2

H3+

H3+, HCO+

H+

H+

H+

e-

e-

He+

He+, C+

OHC

OCO

He+

HCO+

HCO+e-

H3+

H2O

CO2

He+

,xx

x

x

H2

P. Stäuber

Why Observe Hydrides?

1. Part of water network (OH+)

2. Interesting also for other networks (CH2, H2S)

3. Tracers for FUV and X-ray emissions

4. New molecules, not observable from ground

CH3

CH3+

CH2

CH4 CH

CH2+

CH+

H2

He+,

H3+,

HCO+ e-

H2FUV

xFUV

FUV

FUVx , FUV

FUV H2

x , H,FUV

x ,FUV

C

FUVH,

H3+, HCO+

FUV ,

FUVH2

P. Stäuber

H2SH3S+ S

H2S+ SH+ S+

SO

SO+H

H2

H, O

H

O

H3+, HCO+, H3O+

H+

O

e-

He+

H+, C+

H2O, e-

CO

CSO2

SH

SO2+

,x

xx

HSO+

H3+, HCO+,

H3O+e-

OH, O2 OH

H3+,

H+

OH, O2

e-

OHH

e-

H2

He+

e-H3+,

HCO+

x

H+,C+

,x

P. Stäuber

Why Observe Hydrides?

1. Part of water network (OH+)

2. Interesting also for other networks (CH2, H2S)

3. Tracers for FUV and X-ray emissions

4. New molecules, not observable from ground

Stäuber, Doty, van Dishoek & Benz, 2005

Stäuber, Doty, van Dishoek & Benz, 2005

Stäuber, Doty, van Dishoek & Benz, 2005Stäuber, Doty, van Dishoek

& Benz, 2005

AFGL 2591, high-mass YSO, 5 104 y

─ no inner X-rays and UV-··- best fit with X-rays and FUV

Stäuber, Doty, van Dishoek & Benz, 2005

AFGL 2591, high-mass YSO, 5 104 y

-··- best fit with X-rays and FUV─ no inner X-rays and UV

Stäuber, Doty, van Dishoeck, Jorgensen and Benz, 2004

Stä

ub

er,

Do

ty, v

an

Dis

ho

ek

& B

en

z, 2

00

5

Stäuber Jørgensen, v.Dishoeck, Doty & Benz, 2006

erg/serg/serg/s

TMC 1, low-mass YSO, Class 1, 105 y

Lx = 1032 erg/s

1030 erg/s

1028 erg/s

Lx = 0 erg/s

Inner FUV radiation and X-rays enhance the formation

of basic hydrides with positive charge (col. dens.)

X-rays/none X-rays/FUV

– CH 11.6 3.4

– CH+ 70000 0.5

– OH 0.6 0.5

– OH+ 1390 358

– SH 3.3 2.2

– SH+ 35000 1400

None = model without YSO X-rays or FUV

X-ray= model with X-rays, but no FUV

FUV = model with FUV, but no X-rays Calculations for AFGL 2591 by Stäuber et al. 2005

FUV/X-ray sensitive

very X-ray sensitive

very FUV sensitive

not sensitive

very X-ray sensitive

slightly X-ray sensitive

Main formation reactions in YSO envelopes due to X-rays

– CH2 + H → CH + H2

– H3+ + C → CH+ + H2 and HCO+ + C → CH+ + CO

– H2O + γ → OH + H

– H2O + He+ → OH+ + H + He

and H3+ + OH → OH+ + H + H2

– H3+ + S → SH+ + H2

Stäuber et al. 2005

Molecules and Lines

Frequency Transition Remarks Col.depth Prio GHZ (2", AFGL 2591)

CH 536.7 3/2 → 1/2 X-ray tracer, triplet 4.7E+12 ***

1470.7 5/2 → 3/2 4 lines **

1661.1 2 → 1 3 lines **

CH+ 835.1 1 → 0 FUV tracer 4.9E+08 *

1669.1 2 → 1 *

NH 974.5 1 → 0 use? 4.8E+12

NH+ 1038.1 use? 7.9E+08

Molecules and Lines (Cont.)

Frequency Transition Remarks Col.depth Prio GHz

OH already in water program 1.2E+15

OH+ 971.8 1→ 0 X-ray tracer 7.0E+09 * triplet

1892.2 2 → 1 4 lines *

SH 526 2.7E+12 **

1382.9

SH+ 526.05 2 → 1 X-ray tracer, 3.0E+12 **

triplet

Molecules and Lines (Cont.)

FeH All very weak. Why observe?

SiH

PH CaHLiH

Neutral Molecules and Lines: Selection

Frequency Transition Remarks Prio GHz

CH 536,7 3/2 → 1/2 X-ray tracer, ***≈H3O+

1033.0 ?? triplet **

SH 526? ?? X-ray tracer **1382.8 v=1,2 triplet **

Ionized Molecules and Lines: Selection

Frequency Transition Remarks Prio GHz

SH+ 526.05 2 → 1 X-ray tracer, **

triplet **

OH+ 971.8 1→ 0 X-ray tracer *triplet

1892.2 2 → 1 4 lines *

CH+ 835.1 1 → 0 FUV tracer, ≈H2O *1669.2 2 → 1 *

Objects and Strategy

1. Four sources with deep integrations in 7 molecules and 7 lines (each 45 minutes initially)

start with: CH, SH, NH, SH+, OH+, CH+, maybe O2

21 hr2. Twelve sources of Water KP list objects with 4 lines

selected from above (or deeper integrations or second line of selection 1 )

24 hr

6 low-mass stars, class 0 and 1 (with H2O detections)

5 high-mass1 intermediate-mass stars

To Do

1. Vary initial abundances and other parameters

2. Calculate antenna temperature for all lines

3. Select molecules

4. Select lines

5. Select objects from water KP list

6. Ancillary data (ground based observations)