1 ALMA View of Dust Evolution: Making Planets and Decoding Debris David J. Wilner (CfA) Grain Growth  Protoplanets  Debris

2 ALMA and Dust Emission “vibrational” emission is dominant mechanism (thermal fluctuations in charge distribution) longest observable ’s: 0.35 to >3 mm sensitive to cold dust: T<10’s of K samples all disk radii/depths if low opacity, then flux ~ M dust weighted by T dust wavelength dependence of opacity is diagnostic of particle properties, esp. grain size no contrast problem with stellar photospheres unprecedented sensitivity and angular resolution

3 “Protoplanetary” to “Debris” Disks <10 Myr gas and trace dust –dynamics dominated by gas (hydro, turbulence) ~0.001 to 0.1 M  excess: near/mid/far-ir/mm dust particles are sticking, growing into planetesimals up to Gyrs dust and trace gas –dynamics dominated by dust (radiations, collisions) <1 M moon excess: mainly far-ir/mm planetesimals are colliding and creating dust particles SMA Isella et al CSO Marsh et al 

4 collisional growth –sub  m to mm sizes stick at <1 m/s – to km sizes? –too large for chemistry, too small for gravity –collective effects, e.g. layers? vortices? spiral waves? Blum et al. 1998, 2000C. Dominik SiO 2 The Beginning: Particles Stick

5 dust mass opacity model, e.g. power law flux density emitted by disk element dA mm: disk  ~0 to 1 vs. ISM  ~2 (Rayleigh limit) Spectral Signatures of Growth Pollack et al mixture, compact, segregated spheres, n(a) ~ a -q, q=3.5 Calvet & D’Alessio 2001 a max =1 mm a max =10 cm Beckwith & Sargent 1991

6 combine physical model, fluxes, resolved data –irradiated accretion disk model (  ~r -1,T~r -0.5 ) matches (a) SED and (b) resolved 7 & 0.87 mm continuum –shallow mm slope and low brightness require a max > 1 mm Example: TW Hya  =0.7  0.1 Qi et al. 2004, 2006 Calvet et al VLA 7 mm SMA 0.87 mm SED

7 Many Resolved Disks,  Measures ATCA 3mm Lommen et al VLA/PdBI/OVRO Natta et al solid: Lommen et al (10 southern pms stars) dashed: Rodmann et al (10 Taurus pms stars) dotted: Natta et al (7 Ae stars + TW Hya, CQ Tau))

8 ALMA: Resolved “Colors” precision subarcsec spectral index information –couple with disk structure models to account for opacity and temperature variations, localize grain growth S. Andrews no growth inside-out growth

9 Millimeter Sizes Persist Myrs much longer timescale than theory predicts (<1000’s yr) competition between growth and destruction processes? grain size (opacity) need not follow a simple power law are the disks we can study in the millimeter the ones that will never form planets? –probably not: transition disks Weidenschilling 1997 Dullemond & Dominik 2005

10 all indicators of circumstellar material decline, t ~ 5 Myr GM Aur, TW Hya, CoKu Tau 4, DM Tau, … –near/mid-ir flux deficits indicate inner holes (Spitzer) –planet formation? viscous evolution and photoevaporation? Calvet et al “gap” inner disk with bit of ~  m dust r~24 AU inner edge of outer disk Bryden et al Transition Disks ~2 Myr, M * =0.84, M d ~0.09 M 

11 Embedded Protoplanets protoplanet interacts tidally with disk –transfers ang. momentum –opens gap –viscosity opposes –evolve inner holes very active area –viscosity not understood –disk structure not known –inbalance of torques leads to planet migration P. Armitage

12 Example: GM Aur CO 2-1 IRAM PdBI Dutrey et al Schneider et al GHz IRAM PdBI

13 Debris Disks discovered in far-ir: –~15% of main sequence stars show excess: IRAS, ISO, Spitzer ~10 imaged in scattered light and/or thermal emission –highly structured –inner holes, clumpy rings, warps, spirals, offsets, asymmetries –sculpted by planets? Holland et al Greaves et al Smith & Terrile 1984

14 no planets planets –KB dust drifts in –clumpy ring around orbit of Neptune; 3:2  two clumps (cf. “Plutinos”) –nearly empty inner hole due to Jupiter Liou & Zook 1999 Resonant Perturbations P res = P planet (p+q)/p, planet gives periodic kicks structure created when resonances filled by –inward migration of dust due to P-R drag –outward migration of planet traps planetesimals e.g. simulation of dust in our Solar System:

15 Large Dust  Small Dust structure depends on F rad /F grav –largest grains retain resonant parent distribution –intermediate grains librate widely, smooth out –smallest grains are unbound and blown out 3:2 Wyatt 2006 Vega Holland et al Su et al  m 70  m24  m

16 Fossil Record of Planet Dynamics Vega: analogous to Neptune migration? –  a ~7 AU over ~50 Myr (Hahn & Malhotra 1999) Wyatt 2003 Minor Planet Center

17 sensitivity limited with existing facilities the archetype: Vega (350 Myr, A0V, 7.8 pc) at 1.3 mm –compatible images (poor SNR and uv coverage) –dust blobs are robust, spatially extended –stellar photosphere (2 mJy) provides calibration check Higher Angular Resolution? IRAM PdBI: Wilner et al OVRO: Koerner et al. 2001

18 Vega is north (+38 dec) but visible from ALMA site An ALMA Simulation thanks to J. Pety compact configuration: 2x1 350 GHz low surface brightness (model) disk emission –mosaic essential –ACA essential –total power essential –careful treatment of bright star (5 mJy) in imaging and deconv. high fidelity challenging for large, nearby disks modelimage fidelity difference

19 Synoptic Studies resonant structures rotate around star multi-epoch imaging –follow motions of clumps to distinguish models (and exgal. background sources) –Vega: a circular Neptune or an eccentric Jupiter?  Eri rotation ~1”/yr detected (2  ? (Greaves et al. 2005) see Wilner et al and Moran et al. 2004

20 Summary ALMA will qualitatively change nature of dust observations from disks, all evolutionary stages Protoplanetary –grain growth from resolved “colors” Transition Disks –image gaps, holes, related structures Debris Disks –locate planets with resonant particles NASA/ R. Hurt

21 End

22 Schematic Solar System Evolution cloud collapse 10 4 yr planetary system + debris disk 10 9 yr 10 5 yr 100 AU 10 7 yr T star (K) L star Main sequence 8,0005, ,000 protostar + primordial disk planet building protoplanetary disk adapted from Beckwith & Sargent 1996, Nature, 383, 139

23   Cet 5x10 -4 M E  Eri M E Sun <10 -5 M E  Cen 61 Cyg  Ind G,K stars within 4 pc 3 binaries, 2 debris disks (r~60 AU), and the Sun Greaves et al Greaves et al Gyr 7.2 Gyr

24 Planet Detection Parameter Space debris disk structure probes long periods complementary to classical techniques period   mass