Structure and Evolution of Protoplanetary Disks

1. Structure and Evolution ofProtoplanetary Disks Carsten Dominik University of Amsterdam Radboud University Nijmegen

2. What would we like to know? • Formation and Evolution • Spectral Energy Distributions • and what they do and don’t tell us • Grains • Sizes • Composition • Distribution as function of r,z,t • Gas • Mass • Composition • Distribution as function of r,z,t • Dynamics • Rotation and inflow • Disk winds • Viscosity, turbulence, accretion, instabilities

3. Figure from Greene 2001)

4. Disks in a nutshell • Infalling matter has non-zero angular momentum, lands on rotation plane away from star • Star mass dominates, matter on largely Keplerian orbits • Some kind of viscosity couples different annuli of the disk, matter spreads, most falls onto star, some mass moves outward and carries angular momentum • As infall stops, disk mass decreases, eventually disappears into star, planets, or space!

5. Formation & viscous spreading of disk Fig. from C. Dullemond

6. Formation & viscous spreading of disk Hueso & Guillot (2005)

7. Evolution of disks with time • Disks live a few million years Near-IR disk fraction J. Alves L. Hillenbrand

8. How large are disks? • Hundreds, up to a thousand AUs • In scattered light • Dust millimeter emission • Images in CO mm lines • Different techniques will give different sizes • The mm continuum probes the dust in the disk midplane • Scattered light and CO probe a layer higher • CO lines are brighter than the dust continuum, so disks are larger in the CO lines than in the continuum • Disk size will depend on sensitivity unless sharp outer edge • Surface density • Little direct information in the inner disk • Measured in the outer disk (R>30AU) with continuum maps S  r-1

9. Pre-MS disks are big

10. Disk masses • Dust mass from submm flux, assume k(1mm), gas-to-dust ratio = 100 Mdisk ~ 0.001- 0.1 Msun if k(1mm)~1 cm2/g

11. Dynamics in viscous disk • Keplerian rotation: vφ=(GM*/R*)1/2 • Radial drift toward the star: vR~cs H/R • No vertical motions: vz=0 • Turbulence • vt < cs << vφ

12. N E Rotation from CO mm lines: a velocity gradient across the major axis [Isella et al. 2006] HD163296 : 12CO J=2-1 Mstar = 2.00.5 Msun incl = 45°

13. Deviations from Keplerian: • Hogerheijde 2001 • infall in TMC1 • Pietu et al 2005 • V R 0.41 +/- 0.01 in AB Aur Turbulence in the outer disk is very hard to measure

14. Disk shape and composition • Gas and dust are initially well mixed • Dust dominates the opacity at almost any wavelength • Disk is thick because of hydrostatic equilibrium (pressure against gravity). • Density decreases exponentially with height • When small grains exist and are well mixed, stellar radiation is absorbed at about 4 pressure scale heights.

15. Disks contain warm dust around a star - what it heating the dust? • Viscous dissipation (~(M1/2/r3 *dM/dt) • Stellar radiation (~L*/r2) T Tauri HAeBe

16. Star Disk Disk emission

17. dead? Dust, Gas, Radiation PAH UV small grains, PAH CR,X small(?),large grains Hot gas CO, H2O Ice mantles, H3+ Molecules: CO,HCO+... PDR: atoms, ions, small molecules CI, NeII...

18. Gas temperature gets very high in upper layers Woitke, Kamp, Thi 2009

19. General structure of the disk Fig. from Dullemond et al, PPV

20. Submm allows us to look at the whole disk

21. V-band 24um 33um Mulders et al in prep

22. The snowline, depending on accretion Min et al 2010

25. + Sources of Water in the disk: photo dissociation photo desorption gas phase formation route freeze-out/reformation

26. DM Tau • Integrated for 198 min at 557 GHz and 328 m at 1113 GHz • No significant detection of either ortho or para H2O • weak 6σ detection of 557 GHz line (110 - 101) • Models indicate ice depletion (due to settling?) shallowsample, ~2000 sec Bergin et al 2010

27. Grain sizes and spatial distribution

28. Main grain size processes • Settling • Radial Drift • Turbulent mixing and concentration • Gravitational instabilities?

29. Effects of dust settling Dullemond & Dominik (2004)

30. SED differences in FIR As before, but replacing mass by large grains at the equator instead of removing it

31. Evidence for grain growth Smallgrain Large grain v Boekel et al 2003

32. MostT Tauri disks shows evidence for grain growth Kessler-Silacci et al. 2006,2007 10 mm band 20 mm band Obs Model

33. Radial drift of particles 1AU in 100 ys Weidenschilling 1977, Brauer et al 2008

34. Radial motion changes disk sizes • Mm-sized grains move to below 100 AU in 105 years • Porosity increases life time Takeuchi, Clarke, Lin 2005

35. Sources of relative velocities • Brownian motion • Settling • Radial drift • Coupling and decoupling to turbulent eddies • Complex expression depending on details of turbulence and dust properties (e.g. Ormel & Cuzzi 2007)

36. Relative velocities: Total Brauer et al 2008

37. Coagulation only, different velocity sources Brauer et al 2008

38. 1 cm 1 m Effects of radial motion Brauer et al 2008

39. 1 cm 1 m With fragmentation at 10m/s Brauer et al 2008

40. 1 cm 1 m With higher fragmentation speed 30m/s Brauer et al 2008

41. Observed: Large grains in outer disk Optically thin disk: Testi et al 2001

42. Birnstil et al 2010

43. The inner disk

44. Isella and Natta 2005

45. The location of the inner rim • Including backwarming • Equilibrium temperature of a dust grain in free space

46. Optically thin dust inside the rim

47. Moving the rim with refractory shields Kama et al 2009

48. A selection of inner rim structures

49. Rin=0.03,1,10,30 AU Inner holes: transition objects Calvet et al. 2005

50. Disk evaporation • Photoevaporation by EUV, FUV and X-ray photons, @ <10 and >30 AU • Life times enough for planet formation • Disk survives for 106 years after gap formation • Short-lived disks for M*>3Mo Gorti et al 2009