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?
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
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 (> 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 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 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
Kozai migraion 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 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
planet
binary
host star
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’’