The Hot-jupiter Kepler-17b: Discovery, Obliquity from Stroboscopic Starspots, and Atmospheric Characterization
نویسندگان
چکیده
This paper reports the discovery and characterization of the transiting hot giant exoplanet Kepler17b. The planet has an orbital period of 1.486 days, and radial velocity measurements from the HobbyEberly Telescope show a Doppler signal of 419.5 −15.6 ms . From a transit-based estimate of the host star’s mean density, combined with an estimate of the stellar effective temperature Teff=5630± 100 from high-resolution spectra, we infer a stellar host mass of 1.06 ± 0.07 M⊙ and a stellar radius of 1.02 ± 0.03 R⊙. We estimate the planet mass and radius to be MP = 2.45 ± 0.11MJ and RP = 1.31 ± 0.02RJ. The host star is active, with dark spots that are frequently occulted by the planet. The continuous monitoring of the star reveals a stellar rotation period of 11.89 days, 8 times the the planet’s orbital period; this period ratio produces stroboscopic effects on the occulted starspots. The temporal pattern of these spot-crossing events shows that the planet’s orbit is prograde and the star’s obliquity is smaller than 15. We detected planetary occultations of Kepler-17b with both the Kepler and Spitzer Space Telescopes. We use these observations to constrain the eccentricity, e, and find that it is consistent with a circular orbit (e < 0.011). The brightness temperatures of the planet the infrared bandpasses are T3.6 μm=1880± 100 K and T4.5 μm=1770± 150 K. We measure the optical geometric albedo Ag in the Kepler bandpass and find Ag = 0.10 ± 0.02. The observations are best described by atmospheric models for which most of the incident energy is re-radiated away from the day side. Subject headings: planetary systems — stars: individual (Kepler-17b, KIC 10619192, 2MASS 19533486+4748540) — eclipses — techniques: photometry
منابع مشابه
Starspots and spin - orbit alignment for Kepler cool host stars
The angle between the spin axis of the host star and the orbit of its planets (i.e., the stellar obliquity) is precious information about the formation and evolution of exoplanetary systems. Measurements of the Rossiter-McLaughlin effect revealed that many stars that host a hot-Jupiter have high obliquities, suggesting that hot-Jupiter formation involves excitation of orbital inclinations. In t...
متن کاملA Low Stellar Obliquity for Wasp-47, a Compact Multiplanet System with a Hot Jupiter and an Ultra-short Period Planet
We have detected the Rossiter-Mclaughlin effect during a transit of WASP-47b, the only known hot Jupiter with close planetary companions. By combining our spectroscopic observations with Kepler photometry, we show that the projected stellar obliquity is λ = 0± 24. We can firmly exclude a retrograde orbit for WASP47b, and rule out strongly misaligned prograde orbits. Low obliquities have also be...
متن کاملLow Stellar Obliquities in Compact Multiplanet Systems
We measure the sky-projected stellar obliquities (λ) in the multiple-transiting planetary systems KOI-94 and Kepler-25, using the Rossiter-McLaughlin effect. In both cases the host stars are well-aligned with the orbital planes of the planets. For KOI-94 we find λ = −11±11◦, confirming a recent result by Hirano and coworkers. Kepler-25 was a more challenging case because the transit depth is un...
متن کاملKEPLER-63b: A GIANT PLANET IN A POLAR ORBIT AROUND A YOUNG SUN-LIKE STAR
We present the discovery and characterization of a giant planet orbiting the young Sun-like star Kepler-63 (KOI-63, mKp = 11.6, Teff = 5576 K, M⋆ = 0.98M⊙). The planet transits every 9.43 days, with apparent depth variations and brightening anomalies caused by large starspots. The planet’s radius is 6.1± 0.2 R⊕, based on the transit light curve and the estimated stellar parameters. The planet’s...
متن کامل2 9 Se p 20 14 Kepler - 424 b : A “ Lonely ” Hot Jupiter That Found A Companion
Hot Jupiter systems provide unique observational constraints for migration models in multiple systems and binaries. We report on the discovery of the Kepler-424 (KOI-214) two-planet system, which consists of a transiting hot Jupiter (Kepler-424b) in a 3.31-d orbit accompanied by a more massive outer companion in an eccentric (e = 0.3) 223-d orbit. The outer giant planet, Kepler424c, is not dete...
متن کامل