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Using the Inner Oort Cloud to Explore the History of the Earth and Sun

Using the Inner Oort Cloud to Explore the History of the Earth and Sun. Nathan Kaib Advisor: Tom Quinn Collaborators: Andrew Becker, Lynne Jones University of Washington. Outline. Background Outer Solar System primer Inner vs. outer Oort Cloud Observations

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Using the Inner Oort Cloud to Explore the History of the Earth and Sun

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  1. Using the Inner Oort Cloud to Explore the History of the Earth and Sun Nathan Kaib Advisor: Tom Quinn Collaborators: Andrew Becker, Lynne Jones University of Washington

  2. Outline Background • Outer Solar System primer • Inner vs. outer Oort Cloud Observations • Candidate inner Oort Cloud objects • Prospects from future surveys What We Can Learn • Oort Cloud formation and the Sun’s birth environment • Comet showers and mass extinctions

  3. Outline Background • Outer Solar System primer • Inner vs. outer Oort Cloud Observations • Candidate inner Oort Cloud objects • Prospects from future surveys What We Can Learn • Oort Cloud formation and the Sun’s birth environment • Comet showers and mass extinctions

  4. Classical Kuiper Belt (pre ~1995) • Leftover primordial disk • Low inclination • Low eccentricity

  5. Scattered Disk • Objects that have had Neptune encounter • Inclinations inflated • - ( 0 – ~20o) • Higher eccentricities • (0.1 – ~1) • Source of short-period comets

  6. Outer Solar System Oort Cloud extends to ~200,000 AU (1 pc)

  7. Source of Long-Period Comets

  8. Long-Period Comets

  9. The tide of the Milky Way also perturbs the Oort Cloud (COBE, NASA)

  10. About 2x as powerful as stellar passages (Heisler & Tremaine 1986) Galactic tide causes perihelion and inclination to oscillate

  11. Outline Background • Outer Solar System primer • Inner vs. outer Oort Cloud Observations • Candidate inner Oort Cloud objects • Prospects from future surveys What We Can Learn • Oort Cloud formation and the Sun’s birth environment • Comet showers and mass extinctions

  12. X

  13. 25000 AU Jupiter-Saturn Barrier • Comets must have large perihelion shift to make it past Jupiter/Saturn in one orbital period • Only weakly bound comets will have large perihelion changes • Jupiter/Saturn shield inner solar system from inner 20,000 AU of Oort Cloud

  14. 25000 AU a > 1,000 AU ~ LPCs and Oort Cloud • LPCs near Earth only constrain outer Oort Cloud • LPCs beyond Saturn will sample inner Oort Cloud as well a > 20,000 AU

  15. Outline Background • Outer Solar System primer • Inner vs. outer Oort Cloud Observations • Candidate inner Oort Cloud objects • Prospects from future surveys What We Can Learn • Oort Cloud formation and the Sun’s birth environment • Comet showers and mass extinctions

  16. SDSS-II SN Survey Observations 2006 SQ372

  17. SDSS-II SN Survey Observations 2006 SQ372

  18. SDSS-II SN Survey Observations 2006 SQ372

  19. SDSS-II SN Survey Observations 2006 SQ372

  20. a = 796 AU q = 24.2 AU i = 19.5° Orbit Summary

  21. Orbital Evolution Current orbit is transient - unstable after ~200 Myrs!

  22. x semimajor axis perihelion Two Different Origin Scenarios1. Scattered Disk

  23. x semimajor axis perihelion Two Different Origin Scenarios2. Oort Cloud OC SD

  24. Simulations Oort Cloud • 106 particles • Orbit distributions based on Kaib & Quinn (2008) sims • Run for 1.4 Gyrs Scattered Disk • 2,500 particles • Orbit distributions based on SDO observations • Run for 4.5 Gyrs Non-symplectic variable timestep integrator based on SWIFT (Levison & Duncan, 1994; Kaib & Quinn, 2008)

  25. Results – OC Sim.(10° < i < 30°)

  26. Results – OC Sim. (10° < i < 30°)

  27. Results – OC Sim.(10° < i < 30°)

  28. Results – OC Sim.(10° < i < 30°)

  29. Results – OC Sim. (10° < i < 30°)

  30. Orbital Residence Map (OC) 10° < i < 30° X 2006 SQ372

  31. Calibrating Simulation Output • For scattered disk simulation, assume: • NJFCs = 250 • Dormant:Active Comet ratio = 2 (Morbidelli & Fernandez, 2006) • For Oort Cloud simulation, assume: • LPC flux (q < 5 AU) = 1.5 comets/yr (Neslusan, 2007) • Inner:Outer OC population ratio = 3 (Kaib & Quinn, 2008)

  32. Orbital Residence Map (OC) 10° < i < 30° X 2006 SQ372

  33. POC/PSD Map 2000 OO67 SQ372 2006 SQ372 (Kaib et al., 2009) For 2006 SQ372: POC/PSD 16

  34. Origin Implications • 2006 SQ372 is at least 16 times more likely to come from the Oort Cloud compared to the Scattered Disk • Which region of the Oort Cloud?

  35. Inner Oort Cloud Origin Semimajor axis drawdown time vs. Perihelion drift time Dq = -10 AU  Ejection by Saturn Dq = 10 AU  a is fixed

  36. Inner Oort Cloud Origin Sampled by Known LPCs (~2.5%) tq ~ a-2 ta ~ 100 Myrs a < 800 AU 20 AU < q < 30 AU (Kaib et al., 2009)

  37. 2006 SQ372 Summary • 2006 SQ372 and 2000 OO67(Elliot et al. 2005) are first detected members of inner Oort Cloud population inside planetary region • Pan-STARRS, LSST will discover 100’s to 1000’s of similar bodies • Population statistics will constrain structure and population size of inner Oort Cloud

  38. Outline Background • Outer Solar System primer • Inner vs. outer Oort Cloud Observations • Candidate inner Oort Cloud objects • Prospects from future surveys What We Can Learn • Oort Cloud formation and the Sun’s birth environment • Comet showers and mass extinctions

  39. How did the Oort Cloud form? Pat Rawlings, NASA

  40. Planetesimal Scattering q is ~fixed, but a undergoes random walk

  41. ~ 104 AU Inclination also changes If q > 40 AU then growth in a stops

  42. Perihelion (AU) Semimajor axis (AU) t = 2 Gyrs (Kaib & Quinn, 2008)

  43. Perihelion (AU) Semimajor axis (AU) Sedna x OC Buffy x 2004 VN112 x x 2000 CR105 KB SD LPCs t = 2 Gyrs (Kaib & Quinn, 2008)

  44. ~ 103 AU Extended Scattered Disk • If q was always big, orbit should be circular, low i • a is too small for current external forces to shift q

  45. Early Strong Perturbations Embedded Cluster Environment (Brasser et al., 2006) Open Cluster Environment (Kaib & Quinn, 2008)

  46. med min Reproducing ESDOs Brasser et al. (2006) Median OC Distance (AU) Kaib & Quinn (2008)

  47. Birthplace Consequences Inner OC: a < 20,000 AU Outer OC: a > 20,000 AU Kaib & Quinn (2008) • Sun’s birth environment controls inner Oort Cloud enrichment and radial distribution

  48. Outline Background • Outer Solar System primer • Inner vs. outer Oort Cloud Observations • Candidate inner Oort Cloud objects • Prospects from future surveys What We Can Learn • Oort Cloud formation and the Sun’s birth environment • Comet showers and mass extinctions

  49. 25000 AU Comet Showers • Rare close stellar encounters (< 5000 AU) are able to perturb more tightly bound orbits • The Earth is temporarily exposed to the entire Oort Cloud

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