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This presentation discusses the discovery of dusty white dwarfs as signposts for planets. It explores the attribution of infrared excess to dust, the presence of metal pollution in white dwarfs, and the composition of exoasteroids. The Wide-field Infrared Survey Explorer (WISE) mission is highlighted as a significant contributor to this research.
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Born Again Disks as Signposts for Planets • John H. Debes • Space Telescope Science Institute
Dusty White Dwarfs are Signposts for Planets • In 1987, the ZZ Ceti G29-38 was discovered to have an infrared excess • Excess first attributed to brown dwarf, eventually attributed to dust (i.e. Graham et al., 1991) Zuckerman & Becklin (1987)
Rin=10 RWD Rout=30 RWD Data from Reach et al. (2005)
Structure After Jura (2003), Jura et al., (2007), Reach et al., (2009) Dust Sublimation Tidal Disruption Radius
Gaseous WD Disks Are Signposts Slide from B. Gaensicke
Metal line White Dwarfs are Signposts for Planets • G29-38 also showed absorption lines due to Ca, Mg, and Fe • Large telescopes with high resolution spectrographs discovered that 25% of WDs have metal pollution (Zuckerman et al., 2003; Koester et al., 2005) Debes et al. (2010)
Zuckerman et al. (2007) Composition
COS can find exquisite abundances Gaensicke et al. (2011, in prep)
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Planetesimal Survival Dong et al., (2010)
Survival of Planetesimals Sublimation Lmax=2x104 Lʘ Gas Drag 3 Mʘ 1.5 Mʘ Lmax=104 Lʘ 1 Mʘ
How do you get asteroids in? Unstable Planets Debes & Sigurdsson (2002)
Exterior Resonances Bonsor et al., (2011)
Interior Resonances Debes et al., in prep
Gaensicke COS Survey Accretion from Interior Resonances Debes et al., in prep
Predict Belt Masses from Polluted WDs Debes et al., in prep
National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology WISE Mission Overview • Science • Sensitive all sky survey with 8X redundancy • Find the most luminous galaxies in the universe • Find the closest stars+brown dwarfs to the sun • Provide an important catalog for JWST • Provide lasting research legacy Wide-field Infrared Survey Explorer • Salient Features • 4 imaging channels covering 3 - 25 microns wavelength • 40 cm telescope operating at <17K • Two stage solid hydrogen cryostat • Delta launch from WTR on December 14, 2009 • Sun-synchronous 6am/6pm 500km orbit • Scan mirror provides efficient mapping • Operational life: estimate 11 months • 4 TDRSS tracks per day
National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology PI: Edward L. Wright - UCLA • Amy Mainzer - JPL • John Mather - GSFC • Ian McLean - UCLA • Robert McMillan - UA • Bryan Mendez - UCB • Deborah Padgett - IPAC • Michael Ressler - JPL • Michael Skrutskie - UVa • Adam Stanford - LLNL • Russell Walker - MIRA • Dominic Benford - GSFC • Andrew Blain - Caltech • Martin Cohen - UCB • Roc Cutri - IPAC • Peter Eisenhardt -JPL • Nick Gautier - JPL • Tom Jarrett - IPAC • Davy Kirkpatrick - IPAC • David Leisawitz - GSFC • Carol Lonsdale - NRAO
The WIRED Team Stefanie Wachter, (IPAC, lead) Don W. Hoard (IPAC) Dave T. Leisawitz (GSFC) Martin Cohen (MIRA)
WISE Nominal Sensitivities Debes et al., ApJS, submitted
The Take Home Messages • Dusty/Polluted/Gaseous Disk WDs need at least ONE giant planet to exist • Mass and location of such planets may be constrained (and observed in the future with HST/JWST) • IR+photospheric absorption lines give you detailed composition of exoasteroids
Take Home Messages-2 • WIRED will provide a host of new candidates that need to be confirmed and characterized • WIRED will provide variability info for known dusty white dwarfs • WISE will provide legacy information as known WDs become complete to ~100pc (currently, only complete to ~20pc) • Preliminary WISE catalogue is publicly available