A New “Radio Era” for Planet Forming Disks

1. A New “Radio Era” for Planet Forming Disks SMA ALMA EVLA K. Teramura UH IfA David J. Wilner Harvard-Smithsonian Center for Astrophysics thanks to S. Andrews, C. Qi, and many collaborators,www.cfa.harvard.edu/disks HIA, Victoria, March 2013

2. Stars Form with ProtoplanetaryDisks Silhouette Disks in Orion Nebula around ~1 Myr-old stars planets orbiting HR 8799 Marois et al. 2010, Keck Observatory McCaughren & O’Dell 1995 How do disks evolve and form planetary systems?

3. Relevance of Radio Astronomy • low dust opacity mass, particle properties • many spectral lines gas diagnostics, kinematics • access cold material including disk mid-plane • contrast with star planet-forming region • low T, tlow brightness imaging needs sensitivity ALMA EVLA

4. From Dust to Planets requires growth by 14 orders of magnitudes in size in a few Myr through several physical processes… collisional destruction collective effects??? Planetesimal formation Planet formation Debris gravity- assisted growth collisional agglomoration radial drift fragmentation/ bouncing gas capture 1mm 1mm 1m 1km 1000km <1km

5. Spectral Signatures of Grain Growth thermal dust emission Iν∝Bν(T) (1 - e-τν) ≈ ν2TκνΣ Iν∝ ν2+b indexbis observable an diagnostic of the particle size distribution amax = 1μm 1 mm 5 cm Beckwith & Sargent 1991 Miyake & Nakagawa 1993 Draine 2006 1 m b 0 2 “pebbles” ISM grains see Draine 2006 b Rodmann et al 2006 Ricci et al. 2010, 2011

6. Disks@EVLA Key Project PI Claire Chandler (NRAO) + 17 co-Is worldwide grain growth and substructure in protoplanetary disks probe last observable link in chain from ISM dust to planets photometry of 60+ disks at 7/9/13/50 mm imaging of subsets, some to 50 mas = few AU Isella et al. 2010 RY Tau: CARMA • global b: weak model constraints • average level of grain growth only • resolved colors, b(r), affected by • turbulence • particle collision model • materials • radial drift efficiency Birnstiel et al. 2010 95% confidence

7. EVLA Taurus Disk Images Chandler et al, in prep l = 9 mm (30.5 and 37.5 GHz) θ~ 0.7 arcsec = 100 AU spectral indices

8. UZ Tau Resolved Millimeter Colors radiative transfer: tn(r) 100 AU • disk resolved at 0.9 -9 mm • b(r) = d log tn(r) / d log n amax ~ 10 cm (inner disk) amax ~ 10 mm (outer disk) radial drift limited growth? Harris et al. 2013, also Perez et al. 2012

9. Isolating the Effects of Radial Drift thermal pressure: vgas < vKep small sizes: entrained by gas mid sizes: strong headwind large sizes: drag is weak Weidenschilling 1977 • natural size-sorting of solids • strong variation of gas:dust as a function of disk radius

10. The TW Hya System • closest gas-rich disk system (51 pc) • M = 0.6 M,age 3-10 Myr, • southern, isolated, viewed nearly face-on • many studies with SMA • good model of disk physical structure HST Weinberger et al. 2002 Qi et al. 2008 Andrews et al. 2012

11. Indirect Signature of Radial Drift RT model dust densities assume constant gas:dust non-LTE model gas (CO) compare with data link with work on β(r): constraints on drift rates • gas/dust size discrepancy Andrews et al. 2012 Rosenfeld et al. 2013

12. Signatures of Grain Growth and Drift • empirical dependence between dust disk extent and wavelength • emission becomes more compact at longer wavelengths • power law index of opacity, b, decreases with disk radius • maximum particle size increases with disk radius • CO gas disk extent much larger than millimeter dust disk • dust and gas surface density profiles are decoupled • observations naturally explained if growth and inward drift of solids concentrates large particles relative to molecular gas reservoir • planet-disk interactions also make pressure bumps/particle traps

13. Snow Lines and Planet Formation “snow line” = boundary where volatiles condense out of gas phase enhance planetesimal formation dramatically increase available solids increase grain stickiness (icy mantles) influence bulk composition, e.g. C/O key evaporation temperatures H2O: 170 K (R = a few AU) CO: 20 K (R = a few 10’s of AU) Ciesla & Cuzzi 2006 Oberg et al. 2011 Hayashi 1981

14. disks are 3D objects: “snow line” = “snow surface” very difficult to discern in (optically thick) CO emission use chemical selectivity to advantage N2H+ abundant only where CO highly depleted CO inhibits N2H+ formation CO speeds up N2H+ destruction CO freezes out at 20 K observed in pre-stellar cores CO Snow Line and N2H+ Chemistry Qi et al. 2012 N2H+ CO N2 CO HCO+ H3+

15. TW Hya SMA Obs ALMA Prediction SMA N2H+ data model simulation

16. TW Hya ALMA Cycle 0 N2H+ Imaging 2011.0.00340.S PI Qi • 2012 November 18 • l= 0.8 mm (band 7) • 26 antennas, 2 hours • beam 0.6x 0.6 arcsec • rms = 25 mJy (0.1 km/s) >20x better sensitivity, >20x smaller beam area than SMA N2H+obs • N2H+ shows a ring • rim radius (27 AU) matches prediction for CO snow line • N2H+ abundant where Tdrops below 20 K

17. Planetesimal Belts in Debris Disks • sister stars in the 12 Myr-old bPic Moving Group • surrounded by dusty disks, cleared of gas, viewed edge-on • Pic • A6 • 19.4 pc • Rdisk > 800 AU AU Mic M1 9.9 pc Rdisk > 200 AU Kalas 2004

18. Scattered Light Midplane Profiles both disks show broken power-law profiles with similar slopes Liu 2004 Golimowski et al. 2006 AU Mic break at R ~35 AU bPic break at R ~120 AU R-1 R-4 R-1 R-4

19. The “Birth Ring” Paradigm • a collisional ring of dust-producing planetesimals • small grains blown out by stellar radiation (bPic) and winds (AU Mic) • large grains stay close to birth ring • size-dependent dust dynamics explains scattered light profile Strubbe & Chiang 2006 (also see Augereau & Beust 2006) scattered light b = F*/Fgrav Krivov 2010 (see Wyatt 2006)

20. SMA: 1.3 Millimeter Emission Belts bPic AU Mic contours: ±2,4,6 x 0.4 mJy Wilner et al. 2012 contours: ±2,4,6,8 x 0.6 mJy Wilner et al. 2011

21. Emission Models and Belt Locations • bPic • R = 94±8 AU • DR = 34+44 AU • F = 15±2 mJy -32 AU Mic R = 36+7 AU DR = 10+13 AU F = 8.2±1.2 mJy -16 -8

22. AU Mic ALMA Cycle 0 Observations 2011.0.00142.S PI Wilner 2011.0.00274.S PI Ertel • 4 SB executions in 2012 April and June • l= 1.3 mm (band 6) • 16 to 20 antennas • beam 0.8 x 0.7 arcsec (8 x 7 AU) • rms = 30 μJy >10x better sensitivity, >10x smaller beam area than SMA study MacGregor et al. 2013

23. Millimeter Emission Model Fitting contours: ±4,8,12,.. x 30 μJy outer belt + central peak

24. AU MicOuter Dust Belt Properties • extends to R=40 AU, to the break in scattered light profile • consistent with model based on size-dependent dust dynamics • appears sharply truncated • reminiscent of the classical Kuiper Belt • initial condition? or result of dynamical interaction? • surface density profile rises with radius, S(r) ~ r2.8 • collisional depletion of inner disk by ongoing planet formation? • no detectable asymmetries in structure or position • no significant clumps, e.g. due to resonances with orbiting planet • centroid offset limit compatible with presence of Uranus-like planet Kennedy and Wyatt 2010 Mustill and Wyatt 2009

25. AU MicCentral Peak Emission • stellar photosphere and additional unresolved emission • measure 320 mJy in central component • a NextGen stellar model (3720 K, 0.11 L 0.6 M) 52 mJy • stellar flares? • no detectable variability, hours to months • stellar corona? • low radio flux density limits in quiescence from VLA (in early 1990s) • requires turnover frequency > 40 GHz, or time evolution • would be detectable by EVLA at centimeter wavelengths • asteroid-like belt at a few AU? • compatible with absence of excess emission < 25 μm • would be easy for ALMA to resolve in future Cycles

26. A new “Radio Era” for Disk Studies • planets form in circumstellar disks • major unknown is distribution/evolution of cold dust and gas at Solar System scales: key observables for ALMA and EVLA • entering a new regime of decoupled gas and dust, size-dependent dust dynamics • three examples • resolving grain growth and drift • imaging snow lines • revealing planetesimal belts • expect surprises!

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28. Next Generation Radio Telescopes Atacama Large Millimeter Array Expanded Very Large Array • 66 moveable 12m/7m antennas 5000 m site in northern Chile l= 300 mm to 7 mm • global collaboration (NA, EU, EA) to fund >$1B construction • 27 moveable 25 m antennas 2000 m site in New Mexico l= 7 mm to 4 m • modern electronics and signal processing, c. 1980 infrastructure 10-100x better sensitivity, spectral capabilities, resolution

29. Planet-Disk Interactions • viscous/tidal interactions make waves • consequences • open a gap • create pressure bumps • planet migration Andrews et al 2011b Brown et al 2008 Mathews et al 2012 Goldreich & Tremaine 1980; e.g., Bryden et al 1999 Andrews et al 2009 Hughes et al 2009 Andrews et al 2011a Andrews et al 2011a

30. Transition Disk Issues • mass flow across gap • gas: regulated by Mp + viscosity • dust: size-dependent filtration • particle trapping (and growth) • location of ring vs. planet orbit • azimuthal asymmetries Lubow and D’Angelo 2006, Zhu et al. 2012, Dong et al. 2012 Pinilla et al. 2012, Birnstiel et al. 2013 Casassus et al. 2013 ALMA Cycle 0 HD142527

31. A New “Radio Era” for Planet Forming Disks SMA ALMA K. Teramura UH IfA David J. Wilner Harvard-Smithsonian Center for Astrophysics thanks to S. Andrews, C. Qi, and many collaborators,www.cfa.harvard.edu/disks HIA, Victoria, March 2013

32. Planetary Systems Form from Disks Silhouette Disks in Orion Nebula around ~1 Myr-old stars planets orbiting HR 8799 Marois et al. 2010, Keck Observatory McCaughren & O’Dell 1995