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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 • Rossiter-McLaughlin effect and Subaru results • Direct imaging of spin-orbit misaligned systems • Summary and future strategy 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 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 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! Semi-Major Axis Distribution of Exoplanets Snow line Jupiter Need planetary migration mechanisms! 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 Eccentricity Distribution Eccentric Planets Jupiter Cannot be explained by Type I & II migration model Migration Models for Eccentric Planets consider gravitational interaction between planet-planet (planet-planet scattering models) planet-binary companion (Kozai migration) 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 Example of Misalignment Prediction Misaligned and even retrograde planets are predicted. 0 30 60 90 120 150 180 deg Nagasawa, Ida, & Bessho (2008) How can we test these models by observations? 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. The Rossiter-McLaughlin effect When a transiting planet hides stellar rotation, star planet planet the planet hides the approaching side the planet hides the receding side → the star appears to be receding → the star appears to be approaching radial velocity of the host star would have an apparent anomaly during transits. What can we learn from RM effect? The shape of RM effect depends on the trajectory of the transiting planet. well aligned misaligned Radial velocity during transits = the Keplerian motion and the RM effect Gaudi & Winn (2007) 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) Previous studies 1. HD209458 Queloz+ 2000, Winn+ 2005 2. HD189733 Winn+ 2006 3. TrES-1 Narita+ 2007 4. HAT-P-2 Winn+ 2007, Loeillet+ 2008 5. HD149026 Wolf+ 2007 6. HD17156 Narita+ 2008,2009, Cochran+ 2008, Barbieri+ 2009 7. TrES-2 Winn+ 2008 8. CoRoT-2 Bouchy+ 2008 9. XO-3 Hebrard+ 2008, Winn+ 2009, Narita+ in prep. 10. HAT-P-1 Johnson+ 2008 11. HD80606 Moutou+ 2009, Pont+ 2009, Winn+ 2009 12. WASP-14 Joshi+ 2008, Johnson+ 2009 13. HAT-P-7 Narita+ 2009, Winn+ 2009 14. CoRoT-3 Triaud+ 2009 15. WASP-17 Anderson+ 2009 16. CoRoT-1 Pont+ 2009 17. WASP-3 Simpson+ 2010, Tri?+ 2010 18. Kepler-8 Jenkins+ 2010 19. TrES-4 Narita+ 2010 20. HAT-P-13 Winn+ 2010, Hirano+ in prep. Red: Eccentric Blue: Binary Green: Both and more and more Subaru Radial Velocity Observations HDS Subaru Iodine cell 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. 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. 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. Retrograde Exoplanet: HAT-P-7b NN et al. (2009b) Winn et al. (2009) More Retrograde Exoplanets Queloz et al. (2010) WASP-8b WASP-17b Triaud et al. submitted WASP-15b Cameron et al. (2010) WASP-33b 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 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 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 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 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 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) 2007 and 2009 Keck data 2008 and 2010 Subaru data HJD - 2454000 very interesting target for direct imaging observation! 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) Calar Alto / AstraLux Norte Observation: 2009 October 30 Setup: I’ and z’ bands, FoV: 12’’ x 12’’ Total exposure time: 30 sec Lucky Imaging technique (Daemgen+ 09) 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’’ 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. Constraints on outer bodies H band contrast ratio 5σ detectable mass Contrast: [email protected]'’(100AU), [email protected]'’(160AU), [email protected]'’(320AU) Corresponding 5σ detectable mass: 110 MJ, 80 MJ, 70 MJ massive planets and brown dwarfs were not excluded at this point 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) Allowed region for additional bodies Kozai migration forbidden boundary Kozai migration allowed 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) Possible additional planet ‘HAT-P-7c’ Winn et al. (2009c) 2007 and 2009 Keck data 2008 and 2010 Subaru 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 First SEEDS paper 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 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! Many fruits will be harvested from the SEEDS tree!