Decoding Dusty Debris Disks AAAS, Februrary 2014 David J Wilner Harvard-Smithsonian Center for Astrophysics

Debris Disk Primer far-infrared surveys of nearby stars reveal thermal dust emission from reprocessed starlight, F dust /F * < Stapelfeldt et al Fomalhaut star dust images show disks Hubble, Kalas et al dust must be replenished  reservoirs of large bodies

Descendents of Protoplanetary Disks Protoplanetary DiskDebris Disk age< 10 Myr10 Myr to 10 Gyr dust mass> 10 M Earth < 0.1 M Earth gas mass100x dust mass<< dust mass physical picture primordial dust colliding, growing into planetismals planetismals colliding, generating secondary dust 3 Fomalhaut

The Solar System Debris Disk 4 Kuiper Belt (42-48 AU) and asteroid belt (2-3.5 AU) dust-producing bodies in stable belts and resonances ESA A. Felid/STScI encodes planetary system architecture and dynamical history

Debris Disks and Planetary Systems outcomes of planet formation Solar System configuration in context planet detection from disk perturbations habitability of terrestrial planets 5 Fomalhaut  Pictoris HR 8799 HD HD

Millimeter Emission traces Planetesimals 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

20 Myr-old Sister Stars with Debris Disks 7  Pictoris R optical > 800 AU AU Microscopi R optical > 200 AU Kalas 2004

Scattered Light Midplane Profiles “birth-ring” of planetesimals predicted at break in power-law profile Keck, Liu 2004 Hubble, Golimowski et al  Pic break at R =130 AU AU Mic break at R = 40 AU 8 Strubbe & Chiang 2006 scattered light

ALMA Reveals Millimeter Emission Belts 9 Dent et al., submitted  Pic R mm =130 AU MacGregor et al AU Mic R mm = 40 AU Cycle 0, 20+ antennas, 2 hours, <1 arcsecond resolution

AU Mic Millimeter Emission Modeling contours: ±4,8,12,.. x 30 μ Jy outer belt + central peak 10

outer edge at 40 AU, matches break in scattered light profile surface density of planetesimals rises with radius, an outward wave of planet formation? no detectable asymmetries in structure or position (still compatible with presence of a Uranus-like planet) AU Mic Outer Dust Belt Properties 11 T. Pyle/NASA

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 12 Cranmer et al. 2014

AU Mic Higher Resolution Simulations easy to resolve an asteroid belt with 0.25 arcsec resolution a stellar corona will remain unresolved we’ll find out from ALMA in Cycle 1 (PI M. Hughes) 13 Inner Dust BeltStellar Corona

ALMA Observes (half) the Fomalhaut Disk millimeter emission belt narrower than optical scattered light 14 Boley et al Hubble (blue) ALMA (orange) planetesimals confined by shepherding planets? Saturn F Ring

Secondary Molecular Gas in  Pictoris 15 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 sputtering? colliding Mars-mass bodies? Dent et al., submitted

HD 10647: A Very Dusty Debris Disk similar to our Solar System – Sun-like star, F9V type – a Jupiter-like planet at 2 AU – 1000x Kuiper Belt dust at 80 AU What could ALMA see (in an hour)? 16 Stapelfeldt et al Liseau et al ALMA Cycle 2 simulations

Summary debris disks result from collisional cascades of planetesimals, relics of planet formation millimeter emission traces the planetesimals early ALMA observations reveal Kuiper-like belts and (the first of many) surprises 17 ESA

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