1. The University of Tokyo Norio Narita
Subaru HDS Transmission Spectroscopy of the Transiting Extrasolar Planet HD b
The University of Tokyo
Norio Narita
collaborators
Yasushi Suto, Josh Winn, Ed Turner,
Wako Aoki, Chris Leigh, Bun’ei Sato, Motohide Tamura, Toru Yamada

2. Contents Introduction Subaru Observations Data Reduction and Results
Extrasolar Planets
Transmission Spectroscopy
Past Researches
Subaru Observations
Data Reduction and Results
Correction of Instrumental Profiles
Calculation of Difference Light Curves
Resultant Upper limits
Conclusions and Implications

3. Extrasolar Planetary Science
Extrasolar Planets are planets orbiting around main sequence stars other than the Sun.
The first extrasolar planet, 51 Peg. b, was discovered by Michel Mayor et al. in 1995.

4. Motivation for Researches
So far 137 exoplanetary systems have been identified.
We already know that extrasolar planets do exist in the universe, but we do not have enough observational information.
What are there in extrasolar planets?

5. Transmission Spectroscopy
A method to search for atmospheric components of extrasolar planets.
provided by Chris Leigh
At least in principle, one can detect atmospheric components as excess absorption in the in-transit spectra.

6. Our Target HD 209458 Basic data
It is the first extrasolar planetary system in which planetary transits by the companion have been found.
Basic data
HD G0V (Sun-like star) V = 7.64
HD209458b Orbital Period ± days
inclination ± 0.1 deg
Mass ± 0.05 MJ
Radius ± 0.04 RJ
from Extra-solar Planet Catalog ｂｙ Jean Schneider

7. Past Researches From Hubble Space Telescope
2002 An excess absorption of 0.02% in Na D lines was reported.
2003 A strong additional Ly alpha absorption of 15% was found.
2004 Oxygen and Carbon were detected as well.
Charbonneau et al
Vidal-Madjar et al
Vidal-Madjar et al
From ground-based telescopes
For the cores of atomic absorption lines (0.3Å)
Bundy & Marcy (2000) Keck I /HIRES < 3 %
Moutou et al. (2001) VLT /UVES ~ 1 %

8. Subaru Observations
One night observation covering an entire planetary transit was conducted in Oct
Orbital Period
3.5 days
We obtained total 30 spectra:
in 12 out 12 half 6
Observing Parameters
Wavelength 4100~6800Å
Spectral Resolution
SNR / pix ～ 350
Exposure time ～ 500
The phase of observations

9. Create a template spectrum from all of the raw spectra.
Data Reduction Scheme
Create a template spectrum from all of the raw spectra.
Calibrate the template spectrum in total flux and wavelength shift matched to each spectrum.
Calculate residual spectrum and integrate the residual at specific atomic lines.

10. Comparison of Two Spectra
Red and Blue ： two spectra taken 2.5 hours apart
Green ： ratio spectra (Blue / Red)
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11. Correction Method In order to correct the instrumental profiles,
we have established an empirical correction method.
S1 and S2 denote each spectrum, while R = S1/S2, then
(flux calibration)
(wavelength calibration)

12. Correction Result
We could limit instrumental variations almost within the Poisson noise.

13. Difference Spectra We integrate residual over this region. time
template
telluric

14. Difference Light Curves
For example: a difference light curve of Hα line.
There is no transit-related excess absorption (blue region).

15. Comparison with previous results (Bundy and Marcy 2000)
Upper Limits
Comparison with previous results (Bundy and Marcy 2000)
Our upper limits are the most stringent so far from ground-based optical observations.

16. Conclusion and Implication
We performed the first transmission spectroscopy of transiting extrasolar planet using Subaru HDS.
However, we could not detect any transit-related signature.
Our results may imply a limit of photometric accuracy from ground-based observations.
Next we intend to investigate spectroscopic changes caused by planetary transits (i.e. the Rossiter effect).

17. Future Work

18. Implications of our Results

19. The Rossiter-McLaughlin Effect

20. Motivation for Researches
So far 136 exoplanetary systems have been identified.
We already know that extrasolar planets do exist in the universe, but we do not have enough observational information.
What are there in extrasolar planets?
Transmission spectroscopy of transiting extrasolar planets is one of the best clues to study nature of extrasolar planets.