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How Unique Are Nearby Debris Disks?

How Unique Are Nearby Debris Disks?. Alycia Weinberger (DTM/CIW). Dustiness. Are the disks we resolve “typical” for their ages?. * BD+20 307. * HD 92945. * HD 32297. * HD 107146. * HD 69830. Dustiness for their ages. * HD 141569. AU Mic *. L IR / L *. (Spangler et al. 2001).

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How Unique Are Nearby Debris Disks?

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  1. How Unique Are Nearby Debris Disks? Alycia Weinberger (DTM/CIW)

  2. Dustiness Are the disks we resolve “typical” for their ages?

  3. * BD+20 307 * HD 92945 * HD 32297 * HD 107146 * HD 69830 Dustiness for their ages *HD 141569 AU Mic * LIR/L* (Spangler et al. 2001)

  4. Stochastic or Steady-State? (Rieke et al. 2005)

  5. Collisions Make Dust Planet building should generate copious dust. Kenyon & Bromley 2005

  6. Are These Disks Very Dusty? • Dust content actually observed exceeds this calculation: • Primoridial Material? • More planetesimals? • Recent Collisions? HD 141569 HD 32297 (MMSN) Fig 8 of Kenyon & Bromley 2005

  7. Composition

  8. Disk Visible / Near-IR Colors HD 141569A red (V-J; J-K) HR 4796A red (V-J;J-H) b Pic neutral-red (B-I) AU Mic neutral -blue (R-H) HD 107146 red (V-I), ?? (V-J) HD 92945 neutral (V-I) Not Rayleigh Scattering Why?

  9. Color of Silicates

  10. Mid-Infrared Colors Access to temperature information: L=8.25L (b Pic)

  11. Mid-infrared imaging Gemini South (T-ReCS); Telesco et al. 2004 What causes the asymmetry to decrease with wavelength? 12 mm 18 mm

  12. Silicate Distribution: Spatially Resolved Mid-IR Spectroscopy Example: b Pic 8 AU Flux Density (Jy) 16 AU Wavelength (mm) Weinberger et al. 2003, ApJL

  13. Continuum Subtracted Spectra R=0 R=8 AU Silicate Line - Continuum R=16 AU R> 24 AU Wavelength All Silicates Lie Close to the Star -- Planet Induced Collisions? Weinberger et al. 2003

  14. Grain Populations • Only see silicates out to 25 AU • Crystalline silicates centered at star, but small amorphous silicates not! Okamoto et al. 2004, Nature

  15. Ice Sublimation? Reflected & Emitted Light Same ellipticity! Same PA! Different sizes! Weinberger et al. 1999 Marsh et al. 2002

  16. N E New Mid-Infrared Imaging 8 mm (contour) PSF (grayscale) 8 mm (contour) 11.7 mm (grayscale) Disk is same size at 8 & 12 mm! PAHs!

  17. Spatially Resolved Spectra Central Disk Spectrum 24 AU (0.’’24) Terrestrial O3 (Rainbow step every 24 AU) 168 AU (1.’’68) 192 AU (1.92 AU) - Backgd These are all PAHs not Silicates!

  18. Increasing Line Strengths Central Disk Spectrum 24 AU 48 AU 72 AU Flux / Continuum Wavelength (microns) Are PAHs being lifted off grains far from the star? Evidence of gooey organics?

  19. More typical composition • HD 36112 = MWC 758 • Luminosity --- Same! • Age ------------Same! But LIR Much Bigger Crystalline and amorphous silicates lFl/VFv

  20. * BD+20 307 * HD 92945 * HD 32297 * HD 107146 Dustiness for their ages *HD 141569 AU Mic * LIR/L* (Spangler et al. 2001)

  21. CDE1 Forsterite Enstatite Amorphous olivine Amorphous pyroxene Blackbody Signature of Huge Impact? HIP 8920: Small Grains (Song et al. 2005, Weinberger et al 2006)

  22. Silicate Feature -Small Grains HIP 8920 Zodi Reach et al. 2003 Song et al. 2005 Silicate-less Debris Disk (Jura et al.) Fnu (Jy) Hanner et al. 1994 Wavelength (microns)

  23. Formation Region Did the NRDD form in environments similar to the Sun?

  24. b Pic Association (b Pic, AU Mic) Looks Taurus-Like not Orion-Like TW Hy Association (HR 4796) also fairly spread/sparse Song et al. 2003

  25. Kinematic and Youth Selection 800 Pleiades (100 Myr) 700 NGC 2264 (5 Myr) 600 (~8Myr) TW Hydrae 500 Li 6708A Equivalent Width [mA] 400 Eta Chamaeleontis 300 HD 141569 B and C 200 HD 141569 Rejected 100 Possible HD 141569 New 0 A M Members (Kinematic) 0 0.5 1 1.5 2 B-V

  26. b [°] 50 30 10 l [°] Galactic Coords of Young Stars

  27. Where Did the Sun Form? Evidence for “Orion-Like” Environment: • 60Fe with t1/2 = 1.5 Myr Found in Solar System (Tachibana & Huss 2003) • Truncation of the Kuiper Belt (e.g. Kobayashi, Ida & Tanaka 2005) • Formation of Ice Giant and Saturn Compositions (Boss, Wetherill & Haghighipour 2002) • Triggered Star Formation in Ionization Fronts

  28. Ecc. of Exosolar Planets e Courtesy Jean Schneider Exoplanet Encyclopedia

  29. The 6 Year Future • Spitzer detections of new debris disks • Spitzer determinations of disk lifetimes • Spitzer mineralogy of dust • Ground mid-infrared interferometer measurements of inner disks and their compositions • SOFIA searches for H2 emission • HST and AO imaging of Spitzer detected disks • Detection of disk rotation (e Eri) • Detection of planets in disks (ExAO?)

  30. The End

  31. HD 36112 A3 5-10 Myr UX Ori A3 1-2 Myr Flux Density VX Cas A0 1 Myr HD 37258 A2 1-10 Myr Wavelength (mm) Silicate Spectra (thick) Recall that the ages are not well known

  32. Gas : Dust Ratio When Gas:Dust Low and CO/H2 high  Comet Sublimation not primordial gas/dust Roberge et al. 2000, 2002, 2004

  33. A “Real” Debris Disk - Ours! Our Solar System has only a tenuous disk (Zodiacal Cloud) but also has planets [Cassini (1685)] Zodi: 10-10 Mplanets; 100x IR luminosity

  34. Evidence for planets in debris disks What do we look for? Dust sculpted dynamically • Gaps • Asymmetries (e.g. arcs, warps) • Clumps

  35. The Kuiper Belt

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