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Observed Properties of Multiple - Planet Systems

Observed Properties of Multiple - Planet Systems. Properties of Multi-Planet Systems: Outline of Talk. Properties of Single Planets (Review of Last Time) Theory: Migration & Planets Tug on Planets Neptune-Mass Planets: First Observations Multi-Planet Systems: Properties

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Observed Properties of Multiple - Planet Systems

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  1. Observed Properties ofMultiple - Planet Systems

  2. Properties ofMulti-Planet Systems:Outline of Talk • Properties of Single Planets (Review of Last Time) • Theory: Migration & Planets Tug on Planets • Neptune-Mass Planets: First Observations • Multi-Planet Systems: Properties • Mean-Motion Resonances • Formation & Evolution Puzzles

  3. Exoplanet Detection Methods # Planetary Systems Proven Techniques • Precise Doppler: 170 • Transits: 8 • Gravitational lensing: 3 ? • Direct Imaging: 2 ? Techniques for the Future • Astrometry: Precise Doppler Kepler

  4. Review Last Time NASA/JPL 178 Giant Exoplanets Detected Around Sun-Like Stars Doppler Detection of Wobble of Star orbiting common center of mass with planet(s).

  5. Stars Wobble: Gravitational pull of Planets Spectrum of starlight Doppler Effect of Star Light

  6. High Resolution ``Echelle” Starlight From Telescope Echelle Spectrometer Spectrometer CCD Echelle Grating Collimator

  7. Spectrum of Star:Doppler Effect Saturn induces 3 m/s in Sun : 0.001 pixel Doppler Precision: 1 m/s v / c ~ 3 x 10-9 Dl / l ~ 3 x 10-9 4096 Pixels

  8. 1300 FGKM Nearby Stars Three Telescopes Doppler Precision: 3 m s-1 115 Extrasolar Planets 8 Yrs (4 AU) 7 Yrs (3.5 AU) 19 Yrs (6 AU) Keck Lick Anglo-Aus. Tel.

  9. Doppler Precision: 1.0 ms-1Keck HIRES Upgrade (2004) 1 year

  10. Known ExoplanetsJan 1996

  11. 178 • a = 0 - 5 AU • M sini = 0.05-15 MJUP • Multiple Planets • Nearly half found by: Swiss team Harvard teams Texas teams

  12. New Planet P = 5.3 yr e = 0.47 2.96 MJUP

  13. New Planet: P = 1.3 yr e ~ 0.1

  14. Sub-Saturn Masses: 30 - 100 MEarth Msini = 37 MEarth Msini = 32 MEarth Msini = 57 MEarth Sub-Saturn Masses: Detectable for P < 3 Month

  15. Review Giant Planets: Mass Distribution • Rise toward • low masses • to 1 MSAT • Sub-Saturn? Detection Limit: ~ 0.2 MJUP @ 1 AU

  16. Semimajor Axis Distribution 6.5 % Occurrence Poor Detect- ability Flat Extrapolation: D6% of stars have planets 3 - 20 AU . Total: 12 % Rise Prediction: Reservoir of Jupiters at 5-20 AU Log Models: • Inward Migration. • Planets left in place • as disk vanishes .

  17. Future:Gas Giants Orbiting Beyond 5 AU • Represents 5 % • of Stars • Orbits: • Circular or • Eccentric? G0 V

  18. Orbital Eccentricities Tidal Circ.: a < 0.07 AU • <e> = 0.25 • Origin of eccent. controversial . (But suggestion later, and talk by Veras & Armitage) • Ecc still high Beyond 2.5 AU <e>=0.25

  19. Super-Earths: 1 - 14 MEarthThe Next Domain • Earth - Uranus: Gap in Mass: Factor 14 • Intermediate Masses: Do theyForm? Or do planet embryos accrete gas ala Neptune ? • If They Form: - Terr-like: CO2 Atm. ? - Neptune-like H&He env ? • Density: 1 or 5 g cm-3 ? Terrestrial Super- Earths ? Ice & Gas giants

  20. Habitable Worlds and life in the universe

  21. Next Frontier: First Search for Habitable Worlds Too cold Too hot Temp = 0 - 100 C Will Need an Extraordinary, New Telescope To Detect Earth-Like Planets. NASA . . .

  22. NASA’s Effort to:Discover EarthsOrbiting other Stars • Finds Nearby (d< 20 pc) Earths: • Measures masses and orbits. • Follow-up: IR disks, Doppler, Imaging planets (TPF, AO) • First Survey for Earths: • Occurrence rate. • d = 1 kpc, No masses Kepler: SIM:

  23. Observed Properties ofMultiple - Planet Systems

  24. HD 12661 (G0 V) Periodogram P = 5yr

  25. HD 12661: 2 - Planet Model RMS=3.4 m/s Possible 6:1 Resonance Gozdziewski & Maciejewski, Lee & Peale 2.5 MJ 1.9 MJ Weak Interactions

  26. K0V, 1Gy, 16 pc HD 128311 2:1 Resonance Inner Outer Per (d) 458 918 Msini 2.3 3.1 ecc 0.23 0.22 w 119 212 Pc / Pb = 2.004 Dynamical Resonance (Laughlin)

  27. Upsilon Andromedae • First multiple-planet system discovered around a regular “main sequence” star in 1999. SFSU • Now have ~ 450 Doppler observations with precision limited by stellar jitter of ~ 7.5m/s • Upsilon And c & d have significant orbital eccentricities (e = 0.25 & 0.27 ±0.02) • Orbit Eccentricities change during 1000 years. • What is the origin of these eccentricities?

  28. Mass = 0.62 MJUP 60 Days 0.65 0.70 0.75 0.80

  29. Upsilon Andromedae: Velocity Residuals P Tp ecc w K Msini a (d) (JD-2450000) (deg) (m/s) (MJUP) (AU) ----------------------------------------------------------------------------- 4.61712 2.01588 0.028 66.7 68.1 0.66 0.059 241.2 160.4765 0.24 252 55.7 1.97 0.828 1318.4 138.3883 0.28 300 62.2 3.84 2.569 ----------------------------------------------------------------------------- RMS = 15.6 m/s N points = 279 D omega = 48 deg Circulating Or Librating? eC0 ?

  30. . Upsilon Andromedae: Triple Planet System . e=0.27 . 2 MJUP . e=0.25 0 ? . . Impulsive Origin of ecc ? (Ford, Rasio, Malhotra) . 0.6 MJUP . 4 MJup . .

  31. Planet-Planet Scattering: Impulsive Origin Of Eccentricites ?

  32. Upsilon Andromeda:Origin of Eccentricities Initial Eccentricity = 0

  33. Gliese 876Real-Time Mean-Motion Resonanceand first Super Earth: • Star’s Mass = 0.32 Msun • Two Jupiters in 2:1 res.

  34. Two-Planet Model GJ 876: Velocities Resid Time Laughlin et al. 2004

  35. GL 8762:1 Mean-Motion Resonance&Apsidal Lock Inner Outer P 30.1 61.0 d Msini 0.56 1.89 MJ e 0.27 0.10 w 330 333o • Resonance Work: • Laughlin & Chambers • Lissauer & Rivera • Man Hoi Lee & S.Peale

  36. Gliese 876 • 2:1 Mean Motion Resonance Precession Period: 9 yr Man Hoi Lee

  37. Marcy stopped here,as time ran out.

  38. Two-Planet Model GJ 876: Velocities Laughlin et al. 2004

  39. Velocity Residuals to2-Planet fit Period = 1.94 d M sini = 5.9 MEarth For i = 50 deg, MPL = 7.5 MEarth Velocity Lowest Mass Exoplanet to date. Orbital Phase

  40. 3-Planet Fit Rivera & Lissauer

  41. Gliese 876 Two Jupiters in 2:1 Resonance 7 1/2 Earth-Mass Planet 7 1/2 Earth-masses • Excitation of Eccentricity • Tidal Heating

  42. 178 a, MPL, ecc shown20 multi-planet systems151 planet-bearing stars5 Mean-Motion Resonances:Gl 876 (2:1) 55 Cnc (3:1) HD 82943 (2:1) HD 73526 (2:1) HD 128311 (2:1)Proposed M-M Res. : HD 37124 (5:1 ?) HD 12661 (6:1 ?) HD 202206 (6:1 ?)

  43. Compare Multi-Planet systems to single-planet systems

  44. Single-Planet Systems • Planet Mass • Distributions • Neptunes Common • Saturn Paucity • Explanation? M sini (MJUP) Ups And Multi-Planet Systems M sini (MJUP)

  45. Single-Planets Eccentricities: No Sig. Difference; Surprising: Multi-systems should suffer resonances & perturbations GJ 876 Multi-Planets

  46. Summary • Planet Mass Distribution: Peaks Below 1 MSAT • Semimajor Axis Distrib. Rises toward 5 AU • Multi-planet Systems common • Mean-Motion Resonances Common Migration, capture, eccentricity pumping • Properties of Multi-Planets not very different from single-planet systems: Common processes?

  47. Total eccentricity vs Total Planet Mass GJ 876 More mass Higher eccentricity

  48. Planet Mass Ratio GJ 876 Period Ratio Stability of large Mass ratios Requires wide separation

  49. 13 7 GJ 876 Outer planet tends to be more massive.

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