1. Mario van den Ancker – ESO Garching
High Angular Resolution Studies of the Structure of Protoplanetary Disks Surrounding Intermediate-Mass Stars
Mario van den Ancker – ESO Garching
Collaborators: Davide Fedele (MPIA Heidelberg), Gerrit van der Plas (ESO/Univ. Amsterdam), Bram Acke (KU Leuven), Jeroen Bouwman (MPIA Heidelberg), Rens Waters (Univ. Amsterdam), Markus Wittkowski (ESO)

2. Herbig Ae/Be Stars: A Primer
Young (< 10 Myr) intermediate-mass (2-10 solar mass) stars surrounded by protoplanetary disks
Observationally advantageous targets as disks are brighter and more extended than around T Tauri stars
About 200 known in our galaxy

3. Meeus et al. (2001) Classification Scheme Herbig Ae/Be Stars
``Group I’’
``Group II’’

4. Correlations with Meeus et al. classification scheme
Group I (`` flared disks’’)
Group II (``self-shadowed disks’’)
Strong far-IR excess
Weak far-IR excess
Strong PAH emission
Weak or no PAH emission
Strong [O I] emission
Weak or no [O I] emission
Nearby disks resolved in scattered light
Point-sources

5. A Comparison of the Distribution of Gas and Dust in Protoplanetary Disks
Poorly constrained observationally
Two tracers sensitive to the 1-10 AU region for systems at pc:
Gas: [O I] 6300 Å emission line
Dust: Mid-IR (8-13 µm) Interferometry

6. [O I] Emission: VLT/UVES Observations

7. [O I] emission: Non-thermal

8. [O I] emission: Due to photo-dissociation of OH by stellar UV photons in upper layers flared disk

9. HD
Group I = Flared Disk HD
Group II = Self-shadowed Disk

10. VLTI/MIDI Observations (I)
HD (group I = flared disk)

11. VLTI/MIDI Observations (II)
HD (group II = self-shadowed disk)

13. Conclusions
HD : Dust seen further out than [O I] emission; little OH in surface layers past 15 AU?
HD : Scale height of gas larger than dust; disk self-shadowed in dust, but not in gas!
Evolution: from flared disks to self-shadowed disks
Driver: loss of gas-dust coupling in disk atmosphere?