1 / 12 Simultaneous Spectroscopic & Photometric Observations of a Transit of TrES-1b Norio Narita (UT, JSPS Fellow) Collaborators K. Enya (JAXA), B. Sato (Okayama, NAOJ), Y. Ohta, A. Taruya, Y. Suto (UT), J. Winn (MIT), E. Turner (Princeton), M. Tamura, T. Yamada, W. Aoki (NAOJ), Y. Yoshii (UT)

Contents Motivation and Our Project Analysis Method 2 / 12 Contents Motivation and Our Project Analysis Method Preliminary Results Radial Velocities and a Light Curve (e, ω), (V sin Is, λ) contours Transit Center (Tc) and Timing Variation Summary

Observations of Transiting Systems 3 / 12 Observations of Transiting Systems give us various clues to learn more about exoplanets Examples of observable parameters: Spectroscopy (out of transit): RV amplitude K, Minimum Mass MP sin i Eccentricity and Longitude of periastron (e, ω) Period P, Semi-major Axis a, Stellar Rotation Velocity V sin IS Photometry (transit light curve): Inclination i, Radii Ratio RP /RS, Planet Radius RP, True Mass MP, Density ρ, Stellar Limb Darkening Parameter u RM effect (RV anomaly during transit): Angle between Stellar-Spin and Planetary-Orbit Axes λ observable only for transiting systems !

Our Project Simultaneous observations of planetary transits: 4 / 12 Our Project Simultaneous observations of planetary transits: Radial velocity measurements with Subaru 8m Telescope at Mauna Kea, Hawaii. V band photometry with MUGNUM 2m Telescope at Haleakala, Maui.

Target and Purpose Target: TrES-1 (V = 11.8) 5 / 12 Target and Purpose Target: TrES-1 (V = 11.8) Photometry: precisely observed (Winn et al. 2006) Secondary eclipse: detected (Charbonneau et al. 2005) RVs: poorly measured (only ~10 samples so far) Purpose: characterize this system more precisely measure RVs around transit phase (~20 samples) detect the RM effect put constrains for (e, ω) and (V sin Is, λ) determine precise Tc Observations: conducted on UT June 21, 2006 predicted as 238th transit (E = 238 in ephemeris)

Analysis Method χ2 minimization by the amoeba algorithm (Press et al.) 6 / 12 Analysis Method χ2 minimization by the amoeba algorithm (Press et al.) Radial Velocities: computed with the algorithm by Sato et al. (2002) errors are typically 10-15 m/s public data by Alonso et al. (2004) and Laughlin et al (2005) parameters: |K, e, ω, V sin IS, λ|, (i, u), [a, P, RS, RP/RS] free fixed Light Curve: parameters: |Tc(238), i, u|, (e, ω), [a, P, RS, RP/RS] free fixed ||: free parameters (): fixed to the best-fit values of the other dataset []: fixed to values of Alonso et al. (2004) and Winn et al. (2006)

Radial Velocity Fitting 7 / 12 Radial Velocity Fitting All of 31 RV samples best-fit with the RM effect Using χ2 contours, we computed uncertainties of parameters: K = 113.2 ± 4.0 m/s (cf. 115.2 ± 6.2 m/s: Alonso et al. 2004)

Contours : (e, ω) solution 8 / 12 Contours : (e, ω) solution 2 local minima exist: ● 1σ ● 2σ (0.040, 274.4°) χ2 = 16.34, dof = 25 (0.011, 222.9°) χ2 = 15.71, dof = 25 The blue contours are our (e, ω) solutions. The region 90°< ω < 270°, e > 0.003 does not allowed (Charbonneau et al. 2005)

Contours : (VsinIs, λ) solution 9 / 12 Contours : (VsinIs, λ) solution ● 1σ ● 2σ Best fit values: (2360, 42°) 1σ confidence level: λ: 0° ~ 60° (prograde) V sin IS: 1300 ~ 3600 m/s Our result has fairly large uncertainty.. V sin IS constraint (Laughlin et al. 2005) It is still tentative, further observations would be required.

10 / 12 Light Curve Fitting P, RS, RP/RS are fixed to the values in Winn et al. 2006 band: V total: 184 samples photometric accuracy: 0.13% best-fit rms: 0.21% cadence: 60 sec exposure time: 40 or 60 sec Our best-fit values and 1σ uncertainty Tc (238) = 2453907.96400 ± 0.00023 (~20 sec) u = 0.58 ± 0.03, i = 88.4 ± 0.1

Possible Sign of Timing Variation 11 / 12 Possible Sign of Timing Variation Transit Ephemeris: Tc (E) = Tc (0) + E × P Tc (0) = 2453186.80603 ± 0.00028 P = 3.0300737 ± 0.0000026 (Winn et al. 2006) Winn et al. 2006 our result Our result Tc(238) is slightly off from the prediction. Observed – Calculated residuals of Tc may indicate TTV.

Summary We observed a transit of TrES-1b Subaru spectroscopy 12 / 12 Summary We observed a transit of TrES-1b Subaru spectroscopy obtained 20 RV samples with 10~15 m/s uncertainty put constraints on K, (e, ω), (VsinIS, λ) proved a prograde orbital motion of TrES-1b MAGNUM photometry achieved ~2 mmag accuracy determined Tc(238) to within ~20 seconds found an interesting residual in transit timing Details will be reported in Narita et al. in prep.