Simultaneous Subaru/MAGNUM Observations of Extrasolar Planetary Transits Norio Narita (U. Tokyo, JSPS Fellow, Japan) Collaborators Y. Ohta, A. Taruya, Y. Suto, (U. Tokyo) B. Sato, M. Tamura, T. Yamada, W Aoki, (NAOJ) K. Enya, (JAXA) J. N. Winn, (MIT) E. L. Turner, (Princeton) 1 / 18

Two Japanese Telescopes in Hawaii Research Projects –Transmission Spectroscopy –Measurements of the Rossiter effect Previous and Ongoing Work –Sensitivity and Feasibility Future Prospects Contents 2 / 18

Japanese Telescopes in Hawaii Subaru 8.2m Telescope at Mauna Kea, the Big Island MUGNUM 2m Telescope at Haleakala, Maui. 3 / 18

Subaru HDS (High Dispersion Spectrograph) Instrumental performance: for V = 8 stars (in 5000 ~ 6000 Å ) –R ~ 90000, 3 min exposure  SNR ~ 250 / pixel for V = 12 stars –R ~ 45000, 15 min exposure  SNR ~ 100 / pixel HDS is an echelle spectrograph installed at Subaru Telescope. An iodine cell is available for radial velocity measurements. 4 / 18

Multicolor Active Galactic NUclei Monitoring MAGNUM is a dedicated telescope for AGN research. Instrumental performance: FOV : 1’.5 x 1’.5 square, Band : Optical & IR differential photometric accuracy –~ 1.5 mmag (in FOV) –4 ~ 6 mmag (nodding out of FOV) A wide-field camera has not yet been equipped (future planning). 5 / 18

Research Projects using these Telescopes Aim: to characterize exoplanets and their systems through transit observations Ground-based Transmission Spectroscopy –search for atmospheric signatures –previous work : HD Measurements of the Rossiter effect –measure the angle between stellar-spin and planetary-orbital axes –ongoing work : TrES-1 6 / 18

Observing Strategies Simultaneous spectroscopy and photometry: to minimize uncertainty due to orbital ephemeris –important for the Rossiter measurements –transit center accuracy of a few minutes to monitor transient stellar activities –flare, spots, etc Full transit observation within a single night: to limit day-to-day instrumental or telluric variations –important for transmission spectroscopy 7 / 18

Transmission Spectroscopy One can in principle detect atmospheric constituents by comparing spectra taken in and out of transit. 8 / 18

Early Theoretical Models Seager & Sasselov (2000)Brown (2001) -1.71% (peak) -1.53% (base) -1.47% (base) -1.70% (peak) Excess 0.1~0.2% absorption was predicted in alkali metal lines with clouds at low pressure (deep cloud decks). 9 / 18

HST Results Detection of ± % excess absorption for 12 Å band around the sodium doublet: However, it was significantly weaker than the fiducial models (for HD b at least). Charbonneau et al in transitout of transit 10 / 18

Previous Work using Subaru HDS Our sensitivity for HD b was enough to exclude previous fiducial models with a single night observation. Narita et al σ  0.06~0.09% for 2 Å band 1σ  0.04% for the 12 Å band We have attempted to search atmospheric signatures: 11 / 18

Motivation of ground-based observations How about other transiting hot Jupiters? Requirements to exclude fiducial models with one night –very bright host star : V < 8 –transit duration : longer than 1 hour HD would be a second target for this study. We can answer whether the weak sodium absorption is standard or not, or we would be able to detect excess absorption. 12 / 18

Measurements of the Rossiter Effect give us clues to learn about formation mechanism of exoplanets. misalignment parameter λ the degree between the stellar spin axis and the planetary orbital axis in sky projection. 13 / 18

Some Models of Hot Jupiter Formation disk-planet interaction (e.g., Type I & II Migration Theory) core-accretion and radial migration from outside of the snow line λ would be suppressed. (e.g., Solar System: λ ~ 6 deg) if more than 3 giants are formed, the orbits become unstable this leads to the ejection of one of the giants the ejected giant can be recaptured neighbor the host star with ~ 30% probability (S. Ida, private communication) λ would be randomized. planet-planet interaction (e.g., Jumping-Jupiter model) 14 / 18

Past Results All results consistent with zero-misalignment. HD (V = 7.65) –-4.4 ± 1.4 deg (Winn et al. 2005) HD (V = 8.15) –11 ± 14 deg (Wolf et al. 2006) HD (V = 7.67) –-1.4 ± 1.1 deg (Winn et al. ApJL submitted) All hot Jupiters seem to be formed by standard migration theories. 15 / 18

Ongoing Work We observed TrES-1 (V = 11.8) covering a full transit. We have confirmed transit time by photometry, and obtained 23 radial velocity samples (8~10 m/s accuracy). MAGNUM photometry (1σ ~ 0.15%)Subaru spectroscopy (SNR ~ 80) 16 / 18

Motivation and Future Work Planetary systems with large λ have not yet discovered. → Migration mechanism is unique standard? Recent new systems (e.g., HAT-P-1) would be future targets. Requirements to determine λ with good accuracy –bright host star : V < 12 –large stellar rotation velocity : > 2 km/s –large transit depth : ~ 1.5 % –long transit duration : ~ 3 hours see e.g., OTS (2005), Gaudi and Winn (2006) for accuracy of λ. 17 / 18

Summary  Our group has initiated transit observation projects: –Ground-based Transmission Spectroscopy –Measurements of the Rossiter effect  Our targets are: –V < 8 (Transmission Spectroscopy) –V < 12 (the Rossiter measurements) –HD189733, HAT-P-1, etc would be good targets  We wish to provide new observational information through our projects. 18 / 18