References of "Bryson, Stephen T"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailDiscovery and Atmospheric Characterization of Giant Planet Kepler-12b: An Inflated Radius Outlier
Fortney, Jonathan J; Demory, Brice-Olivier; Désert, Jean-Michel et al

in Astrophysical Journal. Supplement Series (2011), 197

We report the discovery of planet Kepler-12b (KOI-20), which at 1.695 ± 0.030 R [SUB]J[/SUB] is among the handful of planets with super-inflated radii above 1.65 R [SUB]J[/SUB]. Orbiting its slightly ... [more ▼]

We report the discovery of planet Kepler-12b (KOI-20), which at 1.695 ± 0.030 R [SUB]J[/SUB] is among the handful of planets with super-inflated radii above 1.65 R [SUB]J[/SUB]. Orbiting its slightly evolved G0 host with a 4.438 day period, this 0.431 ± 0.041 M [SUB]J[/SUB] planet is the least irradiated within this largest-planet-radius group, which has important implications for planetary physics. The planet's inflated radius and low mass lead to a very low density of 0.111 ± 0.010 g cm[SUP]-3[/SUP]. We detect the occultation of the planet at a significance of 3.7σ in the Kepler bandpass. This yields a geometric albedo of 0.14 ± 0.04; the planetary flux is due to a combination of scattered light and emitted thermal flux. We use multiple observations with Warm Spitzer to detect the occultation at 7σ and 4σ in the 3.6 and 4.5 μm bandpasses, respectively. The occultation photometry timing is consistent with a circular orbit at e < 0.01 (1σ) and e < 0.09 (3σ). The occultation detections across the three bands favor an atmospheric model with no dayside temperature inversion. The Kepler occultation detection provides significant leverage, but conclusions regarding temperature structure are preliminary, given our ignorance of opacity sources at optical wavelengths in hot Jupiter atmospheres. If Kepler-12b and HD 209458b, which intercept similar incident stellar fluxes, have the same heavy-element masses, the interior energy source needed to explain the large radius of Kepler-12b is three times larger than that of HD 209458b. This may suggest that more than one radius-inflation mechanism is at work for Kepler-12b or that it is less heavy-element rich than other transiting planets. [less ▲]

Detailed reference viewed: 23 (2 ULg)
Full Text
Peer Reviewed
See detailThe Hot-Jupiter Kepler-17b: Discovery, Obliquity from Stroboscopic Starspots, and Atmospheric Characterization
Désert, Jean*-Michel; Charbonneau, David; Demory, Brice*-Olivier et al

in Astrophysical Journal. Supplement Series (2011), 197

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 ... [more ▼]

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[SUP]+13.3[/SUP] [SUB]-15.6[/SUB] m s[SUP]-1[/SUP]. From a transit-based estimate of the host star's mean density, combined with an estimate of the stellar effective temperature T [SUB]eff[/SUB] = 5630 ± 100 from high-resolution spectra, we infer a stellar host mass of 1.06 ± 0.07 M [SUB]&sun;[/SUB] and a stellar radius of 1.02 ± 0.03 R [SUB]&sun;[/SUB]. We estimate the planet mass and radius to be M [SUB]P[/SUB] = 2.45 ± 0.11 M [SUB]J[/SUB] and R [SUB]P[/SUB] = 1.31 ± 0.02 R [SUB]J[/SUB]. 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°. 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[SUB]g[/SUB] in the Kepler bandpass and find A[SUB]g[/SUB] = 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. [less ▲]

Detailed reference viewed: 10 (0 ULg)