The Hot-Jupiter Kepler-17b: Discovery, Obliquity from Stroboscopic Starspots, and Atmospheric Characterization

Access full-text files




Desert, Jean-Michel
Charbonneau, David
Demory, Brice-Olivier
Ballard, Sarah
Carter, Joshua A.
Fortney, Jonathan J.
Cochran, William D.
Endl, Michael
Quinn, Samuel N.
Isaacson, Howard T.

Journal Title

Journal ISSN

Volume Title



This paper reports the discovery and characterization of the transiting hot giant exoplanet Kepler-17b. The planet has an orbital period of 1.486 days, and radial velocity measurements from the Hobby-Eberly Telescope show a Doppler signal of 419.5(-15.6)(+13.3) m s(-1). From a transit-based estimate of the host star's mean density, combined with an estimate of the stellar effective temperature T-eff = 5630 +/- 100 from high-resolution spectra, we infer a stellar host mass of 1.06 +/- 0.07 M-circle dot and a stellar radius of 1.02 +/- 0.03 R-circle dot. We estimate the planet mass and radius to be M-P = 2.45 +/- 0.11 M-J and R-P = 1.31 +/- 0.02 R-J. 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, eight times 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 degrees. 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's infrared bandpasses are T-3.6 mu m = 1880 +/- 100 K and T-4.5 mu m = 1770 +/- 150 K. We measure the optical geometric albedo A(g) in the Kepler bandpass and find A(g) = 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.



LCSH Subject Headings


Désert, Jean-Michel, David Charbonneau, Brice-Olivier Demory, Sarah Ballard, Joshua A. Carter, Jonathan J. Fortney, William D. Cochran et al. "The hot-Jupiter Kepler-17b: discovery, obliquity from stroboscopic starspots, and atmospheric characterization." The Astrophysical Journal Supplement Series, Vol. 197, No. 1 (Nov., 2011): 14.