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D ecoding Dusty Debris Disks

D ecoding Dusty Debris Disks. David J Wilner Harvard-Smithsonian Center for Astrophysics. AAAS, Februrary 2014. Debris Disk Primer. far-infrared surveys of nearby stars reveal thermal dust emission from reprocessed starlight, F dust /F * < 10 -3. Fomalhaut. star.

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D ecoding Dusty Debris Disks

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

  2. Debris Disk Primer • far-infrared surveys of nearby stars reveal thermal dust emission from reprocessed starlight, Fdust/F* < 10-3 Fomalhaut star Hubble, Kalas et al. 2013 dust Stapelfeldt et al. 2004 • images show disks • dust must be replenished reservoirs of large bodies

  3. Descendents of Protoplanetary Disks Fomalhaut

  4. The Solar System Debris Disk • 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

  5. Debris Disks and Planetary Systems HR 8799 • outcomes of planet formation • Solar System configuration in context • planet detection from disk perturbations • habitability of terrestrial planets Fomalhaut bPictoris HD 95086 HD 106906

  6. Millimeter Emission traces Planetesimals • collisional cascade creates smaller and smaller fragments • micron-size dust blown out • large dust can’t travel far b = F*/Fgrav Krivov 2010 Nature/ISAS/JAXA

  7. 20 Myr-old Sister Stars with Debris Disks • Pictoris • Roptical > 800 AU AU Microscopi Roptical > 200 AU Kalas 2004

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

  9. ALMA Reveals Millimeter Emission Belts Cycle 0, 20+ antennas, 2 hours, <1 arcsecond resolution bPic Rmm=130 AU AU Mic Rmm = 40 AU Dent et al., submitted MacGregor et al. 2013

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

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

  12. AU MicCentral 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 Cranmer et al. 2014

  13. 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) Inner Dust Belt Stellar Corona

  14. ALMA Observes (half) the Fomalhaut Disk • millimeter emissionbelt narrower than optical scattered light Hubble (blue) ALMA (orange) Boley et al. 2012 Saturn F Ring planetesimalsconfined by shepherding planets?

  15. Secondary Molecular Gas in bPictoris • 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

  16. 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)? Stapelfeldt et al. 2007 Liseau et al. 2010 ALMA Cycle 2 simulations

  17. 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 ESA

  18. END

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