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Norio Narita National Astronomical Observatory of Japan

Subaru Measurements of the Rossiter -McLaughlin Effect and Direct Imaging Observations for Transiting Planetary Systems. Norio Narita National Astronomical Observatory of Japan. Outline. Introduction of orbits of Solar system bodies and exoplanets Planet migration models

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Norio Narita National Astronomical Observatory of Japan

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  1. Subaru Measurements of the Rossiter-McLaughlin Effect andDirect Imaging Observations for Transiting Planetary Systems Norio Narita National Astronomical Observatory of Japan

  2. Outline • Introduction of orbits of Solar system bodies and exoplanets • Planet migration models • Rossiter-McLaughlin effect and Subaru results • Direct imaging of spin-orbit misaligned systems • Summary and future strategy

  3. Orbits of the Solar System Planets • All planets orbit in the same direction • small orbital eccentricities • At a maximum (Mercury) e = 0.2 • small orbital inclinations • The spin axis of the Sun and the orbital axes of planets are aligned within 7 degrees • In almost the same orbital plane (ecliptic plane) • The configuration is explained by core-accretion models in a proto-planetary disk

  4. Orbits of Solar System Asteroids and Satellites • Asteroids • most of asteroids orbits in the ecliptic plane • significant portion of asteroids have tilted orbits • 24 retrograde asteroids have been discovered so far • Satellites • orbital axes of satellites are mostly aligned with the spin axis of host planets • dozens of satellites have tilted orbits or even retrograde orbits (e.g., Triton around Neptune) • These highly tilted or retrograde orbits are explained by gravitational interaction with planets or Kozai mechanism

  5. Motivation Orbits of the Solar System bodies reflect the formation history of the Solar System How about extrasolar planets? Planetary orbits would provide us information about formation histories of exoplanetary systems!

  6. Semi-Major Axis Distribution of Exoplanets Snow line Jupiter Need planetary migration mechanisms!

  7. Standard Migration Models Type I and II migration mechanisms • consider gravitational interaction between • proto-planetary disk and planets • Type I: less than 10 Earth mass proto-planets • Type II: more massive case (Jovian planets) • well explain the semi-major axis distribution • e.g., a series of Ida & Lin papers • predict small eccentricities and small inclination for migrated planets

  8. Eccentricity Distribution Eccentric Planets Jupiter Cannot be explained by Type I & II migration model

  9. Migration Models for Eccentric Planets • consider gravitational interaction between • planet-planet (planet-planet scattering models) • planet-binary companion (Kozaimigration) • may be able to explain eccentricity distribution • e.g., Nagasawa+ 2008, Chatterjee+ 2008 • predict a variety of eccentricities and also misalignments between stellar-spin and planetary-orbital axes ejected planet

  10. 0 30 60 90 120 150 180 deg Example of Misalignment Prediction Misaligned and even retrograde planets are predicted. Nagasawa, Ida, & Bessho (2008) How can we testthese models by observations?

  11. Planetary transits transit in the Solar System transit in exoplanetary systems (we cannot spatially resolve) 2006/11/9 transit of Mercury observed with Hinode slightly dimming If a planetary orbit passes in front of its host star by chance, we can observe exoplanetary transits as periodical dimming.

  12. The Rossiter-McLaughlin effect When a transiting planet hides stellar rotation, star planet planet the planet hides the approaching side → the star appears to be receding the planet hides the receding side → the star appears to be approaching radial velocity of the host star would have an apparent anomaly during transits.

  13. What can we learn from RM effect? The shape of RM effect depends on the trajectory of the transiting planet. misaligned well aligned Radial velocity during transits = the Keplerian motion and the RM effect Gaudi & Winn (2007)

  14. Observable parameter λ： sky-projected angle between the stellar spin axis and the planetary orbital axis (e.g., Ohta+ 2005, Gaudi & Winn 2007, Hirano et al. 2010)

  15. Previous studies HD209458 Queloz+ 2000, Winn+ 2005 HD189733Winn+ 2006 TrES-1 Narita+ 2007 HAT-P-2 Winn+ 2007, Loeillet+ 2008 HD149026 Wolf+ 2007 HD17156 Narita+ 2008,2009, Cochran+ 2008, Barbieri+ 2009 TrES-2 Winn+ 2008 CoRoT-2 Bouchy+ 2008 XO-3 Hebrard+ 2008, Winn+ 2009, Narita+ in prep. HAT-P-1Johnson+ 2008 HD80606Moutou+ 2009, Pont+ 2009, Winn+ 2009 WASP-14Joshi+ 2008, Johnson+ 2009 HAT-P-7 Narita+ 2009, Winn+ 2009 CoRoT-3 Triaud+ 2009 WASP-17 Anderson+ 2009 CoRoT-1 Pont+ 2009 WASP-3 Simpson+ 2010, Tri?+ 2010 Kepler-8 Jenkins+ 2010 TrES-4 Narita+ 2010 HAT-P-13 Winn+ 2010, Hirano+ in prep. and more and more Red: Eccentric Blue: Binary Green: Both

  16. Subaru Radial Velocity Observations HDS Subaru Iodine cell

  17. Prograde Planet: TrES-1b Our first observation with Subaru/HDS NN et al. (2007) We confirmed a prograde orbit and the spin-orbit alignment of the planet.

  18. Ecctentric Planet: HD17156b Eccentric planet with the orbital period of 21.2 days. NN et al. (2009a) λ = 10.0 ± 5.1 deg Well aligned in spite of its eccentricity.

  19. Possibly Binary System Planet: TrES-4b NN et al. 2010a. λ = 6.3 ± 4.7 deg NN et al. in prep. Well aligned in spite of its binarity.

  20. Retrograde Exoplanet: HAT-P-7b NN et al. (2009b) Winn et al. (2009)

  21. More Retrograde Exoplanets Quelozet al. (2010) WASP-8b WASP-17b Triaudet al. submitted WASP-15b Cameronet al. (2010) WASP-33b

  22. Summary of previous RM Studies • 4/7: misaligned/eccentric but not binary • 1/4: retrograde/misaligned (eccentric but not binary) • 0/3: misaligned/binary but not eccnetric • 2/2: misaligned/eccentric and binary • 1/2: retrograde/misaligned (eccentric and binary) • 6/15: misaligned/not eccentric nor binary • 4/6: retrograde/misaligned (not eccentric nor binary) • 12/27: misaligned/all, 6/12: retrograde/misaligned • biased, since aligned planets are less interesting and unpublished

  23. Recent speculation for RM results • significant portion of exoplanets seem to have migrated through p-p scattering or Kozai process • ratio of Type I & II migration may be less than previously thought (Winn et al. 2010) • one cannot distinguish between p-p scattering and Kozai migration by spin-orbit misalignments or eccentricities alone • Need to search for counterparts of migration processes • very long term radial velocity measurements • direct imaging

  24. Motivation • Spin-orbit misaligned or eccentric planets should have outer massive bodies to explain their orbits • detection of such bodies are very useful to discriminate planet migration processes of planetary systems • if a binary companion exists • we can constrain its initial configuration of the system based on the Kozai migration, or the system formed through p-p scattering • even if no binary companion exist • such a system formed through p-p scattering • useful to discriminate planet migration mechanisms

  25. SEEDS Project • SEEDS: Strategic Exploration of Exoplanets and Disks with Subaru • First “Subaru Strategic Observations” PI: Motohide Tamura • Using Subaru’s new instrument: HiCIAO • total 120 nights in 5 years (10 semesters) with Subaru • 500+ targets • Direct imaging and census of giant planets and brown dwarfs around solar-type stars in the outer regions (a few - 40 AU) • Exploring proto-planetary disks and debris disks for origin of their diversity and evolution at the same radial regions

  26. Subaru’s new instrument: HiCIAO • HiCIAO: High Contrast Instrument for next generation Adaptive Optics • PI: Motohide Tamura (NAOJ) • Co-PI: Klaus Hodapp (UH), Ryuji Suzuki (TMT) • Curvature-sensing AO with 188 elements and will be upgraded to SCExAO 1024 elements • Commissioned in 2009 • Specifications and Performance • 2048x2048 HgCdTe and ASIC readout • Observing modes: DI, PDI (polarimetric mode), SDI (spectral differential mode), & ADI; w/wo occulting masks (>0.1") • Field of View: 20"x20" (DI), 20"x10" (PDI), 5"x5" (SDI) • Contrast: 10^-5.5 at 1", 10^-4 at 0.15" (DI) • Filters: Y, J, H, K, CH4, [FeII], H2, ND • Lyot stop: continuous rotation for spider block

  27. First Target: HAT-P-7 • not eccentric, but misaligned (NN+ 2009b, Winn et al. 2009) • long-term RV trend (Winn et al. 2009, &unpublished Subaru data) Winn et al. (2009) 2008 and 2010 Subaru data 2007 and 2009 Keck data HJD - 2454000 very interesting target for direct imaging observation!

  28. Observation and Analysis • Subaru/HiCIAO Observation: 2009 August 6 • Setup: H band, DI mode (FoV: 20’’ x 20’’) • Total exposure time: 9.75 min • Angular Differential Imaging (ADI: Marois+ 06) technique with Locally Optimized Combination of Images (LOCI: Lafreniere+ 07) • CalarAlto / AstraLuxNorte Observation: 2009 October 30 • Setup: I’ and z’ bands, FoV: 12’’ x 12’’ • Total exposure time: 30 sec • Lucky Imaging technique (Daemgen+ 09)

  29. Result Images N E Left: Subaru HiCIAO image, 12’’ x 12’’, Upper Right: HiCIAO LOCI image, 6’’ x 6’’ Lower Right: AstraLux image, 12’’ x 12’’

  30. Characterization of binary candidates projected separation: ~1000 AU Based on stellar SED (Table 3) in Kraus and Hillenbrand (2007). Assuming that the candidates are main sequence stars at the same distance as HAT-P-7.

  31. Constraints on outer bodies H band contrast ratio 5σ detectable mass • Contrast: 7x10-4@0.3'’(100AU), 2x10-4@0.5'’(160AU), 6x10-5@1.0'’(320AU) • Corresponding 5σ detectable mass: 110 MJ, 80 MJ, 70 MJ • massive planets and brown dwarfs were not excluded at this point

  32. Initial configuration for the Kozai migration • If either of the candidates is a real binary companion • By the angular momentum conservation (Kozai mechanism) • , : : semi-major axis and eccentricity of planet • : mutual inclination between orbital planes of planet and binary • 0: initial condition, n: now • necessary condition to initiate tidal evolution: • within 82.5 – 97.5 deg (even for the most optimistic case)

  33. Allowed region for additional bodies The kozai migration cannot occur if the timescale of orbital precession due to an additional body PG,c is shorter than that caused by Kozai mechanism PK,B (Innanen et al. 1997) Kozai migration forbidden boundary Kozai migration allowed

  34. Possible additional planet ‘HAT-P-7c’ Winn et al. (2009c) 2008 and 2010 Subaru data 2007 and 2009 Keck data HJD - 2454000 Long-term RV trend ~10 m/s/yr is continuing constraint on the mass and semi-major axis of ‘c’ Kozai migration excluded!, p-p scattering is the most plausible

  35. First SEEDS paper

  36. Further targets • over 10 misaligned planets have been discovered • eccentric planets and planets with long-term RV trend are also interesting • currently no other group than SEEDS has a sufficient observing time for all of these targets! • as is the case for the RM effect, numbers of groups would start similar projects

  37. Summary • RM measurements have discovered numbers of ‘tilted’ planets • tilted and/or eccentric planets are only explained by p-p scattering or Kozai migration • RM measurements cannot distinguish between p-p scattering and Kozai migration from spin-orbit alignment angles • Combination of direct imaging can resolve the problem • there are numbers of interesting targets to pinpoint a planetary migration mechanism • SEEDS can become a pioneer of this study!

  38. Many fruits will be harvested from the SEEDS tree!

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