1 Protoplanetary Disks: An Observer’s Perpsective David J. Wilner (Harvard-Smithsonian CfA) RAL 50th, November 13, 2008 Chunhua Qi Meredith Hughes Sean Andrews (Hubble Fellow) Andrews et al Burrows et al. 1996

2 Circumstellar Disks integral part of star/planet formation paradigm before disks spatially resolved –inevitable consequence of gravity + ang. mom. –Solar System fossil record –preponderance of circumstantial evidence observational challenges –bulk of disk mass is cold (and dark) H 2, probed by minor constituents only –Solar System scales small, difficult to image Shu, Adams & Lizano, 1987 ARA&A 100 AU 140 pc

3 Panchromatic Systems Dullemond et al x-ray uv optical mid/far-ir submm cm hot gas/accr. starlight warm… cool gas & dust dust dominates the opacity, gas dominates the mass

4 optical shadows are beautiful but opaque  mm emission I mm  B (T)(1 - e -  )d  –1 - e -      where  dust emissivity –Rayleigh-Jeans: B (T)  T L mm  ∫  T  M d typical M d  0.01 M  (wide range exists) Disk Masses Andrews & Williams 2007 (cf. Beckwith et al. 1990) for > 300 systems in nearby Taurus and  Oph clouds

5 Disk Mass Distributions “Minimum Mass Solar Nebula” Steady Irradiated  Disk  ~ r -1.5 Weidenschilling 1977 (also Hayashi 1981) D’Alessio et al  ~ r -1.0  c s H (Shakura & Sunyaev 1973)  ~ (dM/dt)/3  (r 1.5 T) -1  r -1  (r) ~ r -p — Adams, Shu & Lada 1988

6 flux limited sample:  Oph (125 pc) and TWA (50 pc) regions 870 microns, 0.25” resolution, surface density structure to r < 20 AU Submillimeter Array Survey

7 SMA Survey (12 disks so far)  Oph TWA 100 AU

8 Surface Density Distributions fit resolved submm data and SED simultaneously –stellar properties –dust properties (uniform) –Dullemond RADMC code (temperature structure computed, not imposed)

9 Surface Density Distributions densities comparable to MMSN (extrapolation) + significant mass reservoir good potential for planet formation (e.g. Inaba et al. 2003, Hubickyj et al. 2005)  r -1 Andrews et al., in prep

10 other two  Oph disks… diminished emission inside r ~ AU growing sample of disks with large central holes Evidence for Central Holes J. Brown, Ph.D. thesis (see Pontoppidan et al. 2008) Andrews et al., in prep mechanism(s)?

11 CO: most abundant gas tracer of H 2 (e.g. Koerner et al. 1993, Mannings et al. 1997, Dutrey et al. 1997, Simon et al. 2000, …) –low J lines collisionally excited, thermalized, optically thick (T  r -0.5 ) –confusion with ambient cloud is often a major problem many other (much weaker) species (e.g. Kastner et al. 1997, Dutrey et al. 1997, van Zadelhof et al. 2003, Thi et al , …) –rich chemistry: ion-molecule, deuteration, photo-, organics –HCO +, DCO +, HCN, CN, DCN, CS, H 2 CO, CH 3 OH, … Isella et al Spectral Line Emission SMA TW Hya CO 3-2 Hughes et al., in prep (Qi et al. 2004, 2006) SMA HD CO 3-2

12 Velocity Fields Keplerian rotation –v  r -0.5 turbulence? –subsonic (if present) TW Hya SMA CO 3-2  v = 44 m/s Hughes et al., in prep

13 Nebular Chemistry D/H enhanced at low temps: H HD  H 2 D + + H 2 +  E is pristine cometary material: “interstellar” or “nebular”? TW Hya: radial distributions of DCO + and HCO + –D/H ratio  from 0.01 to 0.1 from r<30 to 90 AU – in situ fractionation is important Qi et al HCO + 3-2DCO + 3-2

14 Outer Edge Complexity power law models do not match observed extent of dust and CO emission –e.g. HD : 200 AU (dust) vs. 600 AU (CO) –not limited sensitivity –outer disk dust:gas ratio? dust opacity? accretion disk structure: exponential outer edge –reconciles dust and gas sizes with same model SMA 1.3/0.87 mm CO J=3-2 Hughes et al. 2008

15 Disk Magnetic Fields aligned dust grains  linear polarization –models: ~2% pol. fraction 870  m (Cho & Lazarian 2007) –tentative JCMT detections: toroidal field (Tamura et al. 1999) SMA polarimetry of HD –< 5x below model –magnetic field geometry? grain alignment? Hughes et al. in prep

16 Concluding Remarks observed disk properties are “protoplanetary” – dust (Spectral Energy Distributions) –gas (accretion, flaring, mm lines) –sizes 10’s - 100’s AU (dust, mm lines) –masses ~ 0.01 M  (mm dust) –   r -1 (mm dust) –holes cleared by planets? (mm dust) –kinematics Keplerian (mm lines) ALMA on the horizon: full operation 2013? –10-100x sensitivity, resolution, image quality –global partnership to fund >$1B construction –disks are a Key Science Goal

17 END

18 Evidence for Central Holes GM Aur disk: diminished opacity for R < 24 AU C. Espaillat Calvet et al Hughes et al., in prep

19 Transition Disk Models dynamical clearing by planet –planet interacts tidally with disk, transfers angular momentum, opens gap, viscosity opposes (Papaloizou & Lin 1984, …) photoevaporation –accretion rate drops below mass loss rate, open gap: “uv switch” (Clarke et al. 2001,…) demographics favor planets –large masses –modest accretion rates Najita et al. 2007

20 infrared excess 50% (90%) gone by 3 (5) Myr also gas accretion timescale 1-2 Myr T-Tauri stars L mm  ∫B(T)(1 - e -  )d  T  0.01 M  Disk Mass and Disk Dispersal Andrews & Williams 2007 (cf. Beckwith et al. 1990) Hernandez et al (cf. Haish et al. 2001)

21 Disk Evolution: Multiple Paths? B. Merin, Spitzer c2d team primordial disk “cold” disk “anemic” disk debris disk

22 At the Limits of ALMA hypothetical planet in TW Hya disk model density distribution simulated ALMA 900 GHz image Wolf & D’Angelo AU