Aims. We report the discovery of WASP-38b, a long period transiting planet in an eccentric 6.871815 day orbit. The transit epoch is 2 455 335.92050 +/- 0.00074 (HJD) and the transit duration is 4.663 h.
Methods. WASP-38b's discovery was enabled due to an upgrade to the SuperWASP-North cameras. We performed a spectral analysis of the host star HD 146389/BD + 10 2980 that yielded T-eff = 6150 +/- 80 K, log g = 4.3 +/- 0.1, v sin i = 8.6 +/- 0.4 km s(-1), M-* = 1.16 +/- 0.04 M-circle dot and R-* = 1.33 +/- 0.03 R-circle dot, consistent with a dwarf of spectral type F8. Assuming a main-sequence mass-radius relation for the star, we fitted simultaneously the radial velocity variations and the transit light curves to estimate the orbital and planetary parameters.
Results. The planet has a mass of 2.69 +/- 0.06 M-Jup and a radius of 1.09 +/- 0.03 R-Jup giving a density,rho(p) = 2.1 +/- 0.1 rho(J). The high precision of the eccentricity e = 0.0314 +/- 0.0044 is due to the relative transit timing from the light curves and the RV shape. The planet equilibrium temperature is estimated at 1292 +/- 33 K. WASP-38b is the longest period planet found by SuperWASP-North and with a bright host star (V = 9.4 mag), is a good candidate for followup atmospheric studies.
- planets and satellites: detection
- stars: individual: WASP-38
- techniques: photometric
- techniques: radial velocities
- STELLAR ATMOSPHERE MODELS
- LIMB-DARKENING LAW
- HOT JUPITERS
- LIGHT CURVES
- EXTRASOLAR PLANETS
- SURFACE GRAVITIES
- CORALIE SURVEY
- HD 189733B