Evidence for Atmospheric Cold-trap Processes in the Noninverted Emission Spectrum of Kepler-13Ab Using HST/WFC3

Abstract

We observed two eclipses of the Kepler-13A planetary system, on UT 2014 April 28 and UT 2014 October 13, in the near-infrared using Wide Field Camera 3 on the Hubble Space Telescope. By using the nearby binary stars Kepler-13BC as a reference, we were able to create a differential light curve for Kepler-13A that had little of the systematics typically present in HST/WFC3 spectrophotometry. We measure a broadband (1.1$\mu$m to 1.65$\mu$m) eclipse depth of $734\pm 28$ ppm, and are able to measure the emission spectrum of the planet at $R\approx 50$ with an average precision of 70 ppm. We find that Kepler-13Ab possesses a noninverted, monotonically decreasing vertical temperature profile. We exclude an isothermal profile and an inverted profile at more than 3$\sigma$. We also find that the dayside emission of Kepler-13Ab appears generally similar to an isolated M7 brown dwarf at a similar effective temperature. Due to the relatively high mass and surface gravity of Kepler-13Ab, we suggest that the apparent lack of an inversion is due to cold-trap processes in the planet's atmosphere. Using a toy model for where cold-traps should inhibit inversions, and observations of other planets in this temperature range with measured emission spectra, we argue that with more detailed modeling and more observations we may be able to place useful constraints on the size of condensates on the daysides of hot Jupiters.

16 pages, 10 figures, 4 tables. Accepted by AJ; updated to reflect the accepted version

References in corpus (15)

• Can TiO Explain Thermal Inversions in the Upper Atmospheres of Irradiated Giant Planets?
• Theoretical Spectra and Light Curves of Close-in Extrasolar Giant Planets and Comparison with Data
• An ultrahot gas-giant exoplanet with a stratosphere
• The Exoplanet Orbit Database II: Updates to exoplanets.org
• Transmission spectral properties of clouds for hot Jupiter exoplanets
• Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry
• High temperature condensate clouds in super-hot Jupiter atmospheres
• Advection of potential temperature in the atmosphere of irradiated exoplanets: a robust mechanism to explain radius inflation
• Atmospheric Characterization of the Hot Jupiter Kepler-13Ab
• Deciphering the Atmospheric Composition of WASP-12b: A Comprehensive Analysis of its Dayside Emission
• Physical parameters of two very cool T dwarfs
• A Misaligned Prograde Orbit for Kepler-13 Ab via Doppler Tomography
• Atmospheric Characterization of 5 Hot Jupiters with Wide Field Camera 3 on the Hubble Space Telescope
• Near-Infrared Emission Spectrum of WASP-103b using Hubble Space Telescope/Wide Field Camera 3
• SOPHIE velocimetry of Kepler transit candidates VI. An additional companion in the KOI-13 system

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