New Views of Planet-Forming Disks Radio Imaging from SMA to ALMA David J. Wilner Harvard-Smithsonian Center for Astrophysics K. Teramura UH IfA Wesleyan University November 5, C. Qi, K. Oberg, S. Andrews, M. MacGregor +many others SMA ALMA

2 1.Disks and Radio Astronomy 2.Snow Lines 3.Planetesimal Birth Rings

3 1.Disks and Radio Astronomy 2.Snow Lines 3.Planetesimal Birth Rings

Circumstellar Disks John Bally inevitable consequence of collapse + angular momentum integral component of star and planet formation paradigm Orion “Proplyds”

1  m 1mm 1m 1km 1000km <1km Planetesimal formationPlanet formation collisional agglomoration gravity- assisted growth gas capture radial drift fragmentation/ bouncing Debris From Dust to Planets and Debris requires growth by 14 orders of magnitudes in size in a few Myr through multiple physical processes 5 collisional destruction collective effects???

Disks Evolve and Form Planetary Systems Protoplanetary DiskDebris Disk + Planets age< 10 Myr> 10 Myr dust mass> 10 M Earth < 0.1 M Earth gas mass100x dust mass<< dust mass physical picture primordial dust colliding, growing into planetesimals planetesimals colliding, generating secondary dust 6 Silhouette Disks in Orion Nebula around 1 Myr-old stars HR 8799 Solar System Marois et al Copernicus 1543 McCaughren & O’Dell 1995

Relevance of Radio Astronomy low dust opacity mass, particle properties access cold material including disk midplane many spectral lines, heterodyne R~10 7 gas diagnostics, kinematics contrast with star planet-forming region low T,   low brightness imaging needs sensitivity 7

The ALMA Revolution 54 moveable 12m antennas + 12 moveable 7m antennas 5000m site in Chilean Andes wavelengths 0.3 to 3.4mm baselines to 16 km global (NA/EU/EA) collaboration to fund $1.3B construction 8 moveable 6m antennas 4000m site on Mauna Kea, HI wavelengths 0.4 to 1.7mm baselines to 0.5 km SAO/ASIAA collaboration 25x better sensitivity and resolution! 8 ALMA SMA

9 1.Disks and Radio Astronomy 2.Snow Lines 3.Planetesimal Birth Rings

Snow Lines and Planet Formation “snow line” = boundary where volatiles condense out of gas phase 10 Hayashi 1981 H 2 O snow line icy grains bare grains rocky planetesimals icy planetesimals Rocky Planets Gas Giants Ice Giants

Snow Line Implications 11 Oberg et al enhance planetesimal formation – dramatically increase available solids – increase grain stickiness (icy mantles)  multiple snow lines from species with low condensation temps influence planetesimal bulk composition -C/O in planetary atmospheres -H 2 O on planets (habitability)

radial and vertical gradients CO “snow line” = CO “snow surface” -impossible to discern in (optically thick) CO emission -may be teased out with a disk structure model and extensive analysis of resolved multi-transition, multi-isotope CO data (Qi et al. 2011) Disks are 3D Objects 12

CO Snow Line and N 2 H + Chemistry use chemical selectivity to advantage N 2 H + is abundant only where CO highly depleted – CO inhibits N 2 H + formation – CO speeds up N 2 H + destruction – CO freezes out at about 20 K – observed in pre-stellar cores 13

Chemical Effect of CO Freeze-Out 14 HCO + H 2 CO N2H+N2H+ T > CO freeze-out T < CO freeze-out N2H+N2H+ HCO + H 2 CO K. Oberg

CO Depletion in Pre-Stellar Cores 15 N 2 H + and CO anti-correlated in cold, dense cores Lada and Bergin 2003 Bergin et al. 2002

The TW Hya Disk System Weinberger et al closest gas-rich circumstellar disk (~50 pc) – M * ~ 0.8 M , age 3-10 Myr, – southern, isolated, viewed nearly face-on – many studies with the SMA – good model of (outer) disk physical structure 16 Qi, Wilner et al. 2008, Andrews, Wilner et al Hughes, Wilner et al. 2011

TW Hya SMA N 2 H + Data and Model S PI Qi Proposal Rejected!

stuck N 2 H + J=4-3 line into free spw of Cycle 0 program – noted in proposal with no justification – higher excitation transition, not optimal for cold mid-plane – lower angular resolution and less sensitivity…  ALMA N 2 H + Imaging S PI Qi observations – 2012 Nov 18 – 372 GHz – 26 antennas, 2h – 0.6x0.6 arcsec – rms 25 mJy (0.1 km/s) Qi, Oberg, Wilner et al. 2013

Quantifying the N 2 H + Ring Structure 19 assume N 2 H + power-law radial abundance profile RATRAN, fit for R in, R out, index R in = 30 AU  CO snow line T CO freeze-out ~18 K Qi, Oberg, Wilner et al. 2013

ALMA N 2 H + Channel Maps 20 Data Model Residual

Snow Lines in Protoplanetary Disks a series of “snow lines” arise from condensation fronts – impacts planetesimal formation and composition enhanced N 2 H + abundance expected at CO freeze-out – a robust chemical marker for CO snow line 21 ALMA imaging of TW Hya CO snow line at 30 AU validates concept easy to extend to probe thermal effects and chemistry, e.g. do complex organics emerge from CO ice? need to identify chemical marker(s) for the H 2 O snow line

Origins of Organics in Disks S PI Oberg H 2 CO and CH 3 OH form from hydrogenation of CO ice but H 2 CO may also form through gas-phase pathways given the location of CO snow line, easy to discriminate Cycle 2 simulations of TW Hya H 2 CO 3 1,2 -2 1,1 emission (241.7 GHz)

Hints of CO Ice Regulated Chemistry 23 H 2 CO excitation temperature is low (< 20 K) in SMA sample of disks Qi, Oberg, Wilner 2013 SMA images of HD

24 1.Disks and Radio Astronomy 2.Snow Lines 3.Planetesimal Birth Rings

Planetesimal Belts in Debris Disks sister stars in the 20 Myr-old  Pic Moving Group surrounded by tenuous dusty disks viewed edge-on 25  Pic A pc R disk > 800 AU AU Mic M1 9.9 pc R disk > 200 AU Kalas 2004

Scattered Light Midplane Profiles Keck, Liu 2004 Hubble, Golimowski et al  Pic break at R =130 AU AU Mic break at R = 40 AU 26 both disks show broken power-law profiles with similar slopes

The “Birth Ring” Paradigm collisional cascade creates smaller and smaller fragments micron-size dust blown out large dust can’t travel far  = F * /F grav Krivov Nature/ISAS/JAXA millimeter emission traces planetesimals Strubbe & Chiang 2006 scattered light

SMA  Pic Millimeter Emission Belt Wilner et al  Pic contours: ±2,4,6,8 x 0.6 mJy 28  Pic R = 94±8 AU  R = AU F = 15±2 mJy -32

SMA AU Mic Millimeter Emission Belt 29 Wilner et al AU Mic contours: ±2,4,6 x 0.4 mJy AU Mic R = AU  R = AU F = 8.2±1.2 mJy

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

AU Mic Millimeter Emission Modeling contours: ±4,8,12,.. x 30 μ Jy outer belt + central peak 31

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 surface density of planetesimals rises with radius,  (r) ~ r 2.8 – collisional depletion by outward wave of planet formation? AU Mic Outer Dust Belt Properties 32 Kennedy and Wyatt 2010 Kenyon and Bromley 2004 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

AU Mic Central Peak Emission unresolved and 6x stronger than stellar photosphere stellar corona? models can match millimeter and X-ray asteroid-like belt at R<3 AU? compatible with infrared limits 33 Cranmer, MacGregor, Wilner 2014

AU Mic Higher Resolution Simulations easy to resolve an asteroid belt with longer baselines a stellar corona will remain unresolved 34 Inner Dust BeltStellar Corona we’ll find out from Meredith Hughes’s ALMA Cycle 1 program

New Views of Planet-Forming Disks planets form in circumstellar disks major unknown is distribution/evolution of cold dust and gas at Solar System scales: key observables for ALMA examples -imaging the CO snow line -revealing planetesimal belts 35 expect surprises!

36 END

Snow Line Implications 37 e.g. exoplanet chemistry and spectroscopy Mudhusudhan 2012

Secondary Molecular Gas in  Pictoris 38 ALMA detects CO J=3-2 emission 30% from one compact clump icy planetesimals shattered by collisions? – destruction of large comet every 5 minutes – trapping in the resonances of an outer planet could account for localized gas production colliding Mars-mass bodies? Dent et al. 2014

ALMA Reveals Millimeter Emission Belts 39 Dent et al  Pic R mm =130 AU MacGregor et al AU Mic R mm = 40 AU Cycle 0, 20+ antennas, 2 hours, <1 arcsecond resolution

40 Comet 17P/Holmes 2007 Outburst an ordinary Jupiter family comet discovered in 1892 during routine monitoring of Andromeda galaxy orbital period 6.9 years origin believed to be in Kuiper Belt, transported by planet migration largest cometary outburst ever seen (magnitude 17 to 2.8 in 42 hours)

Outburst Significance provides opportunity to measure chemical abundances unprocessed material from interior of the nucleus is released 41

October 26-29, 2007 Millimeter Continuum resolution arcsec ( km) traces millimeter-sized grains in the coma peak locates nucleus dM/dt = 2.6x10 6 kg/s 42

October 26-29, 2007 Integrated Spectra 43 detect HCN, CO, H 13 CN, H 2 CO, H 2 S, CH 3 OH, CS HCN linewidth of about 1 km/s due to outgassing CO (and CS) narrow and offset from cometocentric velocity

Posterior Probability Distributions 44

Consistent with SMA CO Isotope Data 45 SMA observations of 13 CO and C 18 O J=2-1 CO freeze-out