Simultaneous Subaru/MAGNUM Observations of Extrasolar Planetary Transits

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Simultaneous Subaru/MAGNUMObservations of
Extrasolar Planetary Transits
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• 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)

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

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Japanese Telescopes in Hawaii
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Subaru 8.2m Telescope at Mauna Kea, the Big Island
MUGNUM 2m Telescope at Haleakala, Maui.
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Subaru HDS (High Dispersion Spectrograph)
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HDS is an echelle spectrograph installed at
Subaru Telescope.
An iodine cell is available for radial velocity
measurements.

• 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

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Multicolor Active Galactic NUclei Monitoring
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MAGNUM is a dedicated telescope for AGN research.
A wide-field camera has not yet been equipped
(future planning).

• 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)

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Research Projects using these Telescopes
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Aim to characterize exoplanets and their
systems through transit observations

• Ground-based Transmission Spectroscopy
• search for atmospheric signatures
• previous work HD 209458
• Measurements of the Rossiter effect
• measure the angle between stellar-spin and
  planetary-orbital axes
• ongoing work TrES-1

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Observing Strategies
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• Full transit observation within a single night
• to limit day-to-day instrumental or telluric
  variations
• important for transmission spectroscopy

• 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

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Transmission Spectroscopy
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One can in principle detect atmospheric
constituents by comparing spectra taken in and
out of transit.
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Early Theoretical Models
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Excess 0.10.2 absorption was predicted in
alkali metal lines with clouds at low pressure
(deep cloud decks).
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HST Results
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Detection of -0.02320.0057 excess
absorption for 12Å band around the sodium doublet
However, it was significantly weaker than the
fiducial models (for HD 209458b at least).
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Previous Work using Subaru HDS
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We have attempted to search atmospheric
signatures
Our sensitivity for HD 209458b was enough to
exclude previous fiducial models with a single
night observation.
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Motivation of ground-based observations
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How about other transiting hot Jupiters?
We can answer whether the weak sodium absorption
is standard or not, or we would be able to detect
excess absorption.
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Measurements of the Rossiter Effect
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give us clues to learn about formation mechanism
of exoplanets.
misalignment parameter ? the degree between the
stellar spin axis and the planetary orbital
axis in sky projection.
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Some Models of Hot Jupiter Formation
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Past Results
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All results consistent with zero-misalignment.

• HD 209458 (V 7.65)
• -4.4 1.4 deg (Winn et al. 2005)
• HD 149026 (V 8.15)
• 11 14 deg (Wolf et al. 2006)
• HD 189733 (V 7.67)
• -1.4 1.1 deg (Winn et al. ApJL submitted)

All hot Jupiters seem to be formed by standard
migration theories.
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Ongoing Work
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We observed TrES-1 (V 11.8) covering a full
transit.
MAGNUM photometry (1s 0.15)
Subaru spectroscopy (SNR 80)
We have confirmed transit time by photometry,
and obtained 23 radial velocity samples (810 m/s
accuracy).
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Motivation and Future Work
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Planetary systems with large ? have not yet
discovered. ? Migration mechanism is unique
standard?
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Summary
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• Our group has initiated transit observation
  projects
• Ground-based Transmission Spectroscopy
• Measurements of the Rossiter effect
• Our targets are
• V lt 8 (Transmission Spectroscopy)
• V lt 12 (the Rossiter measurements)
• HD189733, HAT-P-1, etc would be good targets
• We wish to provide new observational information
  through our projects.