The chemistry and stability of

1
The chemistry and stability of the protoplanetary
disk surface
Inga Kamp In collaboration with Kees
Dullemond (MPA) Ewine van Dishoeck
(Leiden) Bastiaan Jonkheid (Leiden)
David Hardy, NASA
2
The chemistry and stability of the protoplanetary
disk surface
Inga Kamp In collaboration with Kees
Dullemond (MPA) Ewine van Dishoeck
(Leiden) Bastiaan Jonkheid (Leiden)
David Hardy, NASA
3
Motivation
?
Protoplanetary disk in Orion
Debris disk
4
The basic model
- disk masses 10-4 - 0.01 M Sun - elemental
abundances molecular cloud abundances -
optical properties of dust grains single
'mean' grain size - dust temperature
radiative equilibrium - gas-to-dust mass
ratio variable - UV radiation fields
interstellar radiation field, photospheric
radiation field, photospherechromosphere
5
Vertical density structure in a flaring T Tauri
disk
z/r
Dullemond et al. 2002
log
UV radiation field of a T Tauri star scaled
solar chromosphere IUE data stellar
atmosphere model
CO, H2 photodissociation
Kamp Sammar 2004
6
The chemical structure
-8
Interface disk-remnant gas
-4
0
t 1 layer
H2 is chemically destroyed by O in the hot
regions H2 O ? OH H OH n ? O H
500 K
2000 K
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The chemical structure
Interface disk-remnant gas
t 1 layer

• warm H2 present in disk surface
• layers (thermally excited,
• Tex few 100 K)

• warm surface contains
• observable molecules such as
• e.g. CO, CH, OH

8
The gas temperature
500 K
50 K
2000 K
100 K
Gas and dust couple well above the superheated
surface layer of the disk
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The gas temperature
?
Gas and dust couple well above the superheated
surface layer of the disk
10
Evaporation of the surface
- Gas densities are high enough to couple H to
the remaining species
- Disk surface evaporates inside of 50 AU ?
verify with fully self-consistent

disk models
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Outlook Disk structure models
- self-consistent stationary disk models -
comparison with observations by scanning through
the disk with e.g. VISIR, IRAM, ALMA in the
NIR to submm ? feedback for the models
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Outlook Disk structure models
- self-consistent stationary disk models -
comparison with observations by scanning through
the disk with e.g. VISIR, IRAM, ALMA in the
NIR to submm ? feedback for the models
13
Outlook Disk structure models
- self-consistent stationary disk models -
comparison with observations by scanning through
the disk with e.g. VISIR, IRAM, ALMA in the
NIR to submm ? feedback for the models
- evaporation of the inner disk as a function
of spectral-type of central star (include
X-rays)
- compile heating/cooling tables for
hydrodynamical modeling
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The End