Subaru Measurements of the Rossiter -McLaughlin Effect

1. Subaru Measurements of the Rossiter-McLaughlin Effect and Direct Imaging Observations for Transiting Planetary Systems Norio Narita (NAOJ) and SEEDS/HiCIAO/AO188 teams The full member list is available in poster 1.28 by Kusakabe et al. Migration Models of Close-in Exoplanets How have they migrated to their current positions? binary host star Planetary migration mechanisms and outcomes • Disk-Planet interaction (e.g., Lin et al. 1996, Ida & Lin 2004) • Planets gradually migrate inward within their disks • predicts small eccentricity and small spin-orbit misalignment • Planet-Planet scattering (e.g., Rasio & Ford 1996, Chatterjee et al. 2008, Nagasawa et al. 2008) • gravitational scattering of multiple massive planets and subsequent tidal circularization • possible large eccentricity and spin-orbit misalignment • The Kozai migration in binary systems (e.g., Wu & Murray 2003, Fabrycky & Tremaine 2007) • eccentricity/inclination oscillations induced by a separated binary companion and subsequent tidal circularization • possible large eccentricity and spin-orbit misalignment planet A prediction of spin-orbit alignment angles Nagasawa et al. (2008) How can we test these planetary migration models by observations? The Rossiter-McLaughlin Effect Subaru measurements of spin-orbit alignment angles Direct Imaging for Eccentric/Tilted Systems Discriminating p-p scattering and Kozai migration • 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 • long term radial velocity measurements (< 10AU) • direct imaging (> 10-100 AU) is very interesting TrES-1b: Narita et al. (2007) HD17156b: Narita et al. (2009a) HAT-P-7b: Narita et al. (2009b) SEEDS project • SEEDS: Strategic Exploration of Exoplanets and Disks with Subaru • First “Subaru Strategic Observations” PI: Motohide Tamura • Using Subaru’s new instruments: HiCIAO & AO188 • See poster 1.28 (Kusakabe et al.) and 1.49 (Takahashi et al.) TrES-4b: Narita et al. (2010a) XO-4b: Narita et al. (2010c) HAT-P-11b: Hirano et al. (2010b) Procedure to Constrain Planetary Migration Models by Direct Imaging • Step 2: calculate restricted region for Kozai migration • The Kozai migration cannot occur if the timescale of orbital precession due to an additional body PG,c is shorter than that caused by a binary through Kozai mechanism PK,B (Innanen et al. 1997) • If any additional body exists in the restricted region • Kozaimigraion excluded if • search for long-term RV trend is very important • If no additional body is found in the region → step 3 • both Kozai and p-p scattering still survive • Step 1: Is there a binary candidate? • No! • Kozai migration by a binary companion is excluded • If a candidate exist → step 2 • both p-p scattering and Kozai migration survive • need a confirmation of true binary nature • common proper motion • common peculiar radial velocity • common distance (by spectral type) • Step 3: calculate initial condition for Kozai migration • Based on angular momentum conservation during Kozai migration, we can constrain the initial condition of the system • : initial mutual inclination between the planetary orbit and the binary orbit can be constrained Application of the Methodology to the HAT-P-7 System (Narita et al. 2010b) Long term trend (Winn et al. 2009) Kozai migration forbidden boundary Kozai migration allowed Based on stellar SED (Table 3) in Kraus and Hillenbrand (2007). projected (minimum) separation: 1000 AU Assuming that the candidates are main sequence stars at the same distance as HAT-P-7. Left: Subaru HiCIAO image, 12’’ x 12’’, Upper Right: HiCIAO LOCI image, 6’’ x 6’’ Lower Right: AstraLux image, 12’’ x 12’’