Theoretical Spectra and Light Curves of Close-in Extrasolar Giant Planets and Comparison with Data

Abstract

We present theoretical atmosphere, spectral, and light-curve models for extrasolar giant planets (EGPs) undergoing strong irradiation for which {\it Spitzer} planet/star contrast ratios or light curves have been published (circa June 2007). These include HD 209458b, HD 189733b, TrES-1, HD 149026b, HD 179949b, and $\upsilon$ And b. By comparing models with data, we find that a number of EGP atmospheres experience thermal inversions and have stratospheres. This is particularly true for HD 209458b, HD 149026b, and $\upsilon$ And b. This finding translates into qualitative changes in the planet/star contrast ratios at secondary eclipse and in close-in EGP orbital light curves. Moreover, the presence of atmospheric water in abundance is fully consistent with all the {\it Spitzer} data for the measured planets. For planets with stratospheres, water absorption features invert into emission features and mid-infrared fluxes can be enhanced by a factor of two. In addition, the character of near-infrared planetary spectra can be radically altered. We derive a correlation between the importance of such stratospheres and the stellar flux on the planet, suggesting that close-in EGPs bifurcate into two groups: those with and without stratospheres. From the finding that TrES-1 shows no signs of a stratosphere, while HD 209458b does, we estimate the magnitude of this stellar flux breakpoint. We find that the heat redistribution parameter, P${}_n$, for the family of close-in EGPs assumes values from $\sim$0.1 to $\sim$0.4. This paper provides a broad theoretical context for the future direct characterization of EGPs in tight orbits around their illuminating stars.

Accepted to Ap. J., provided here in emulateapj format: 28 pages, 8 figures, many with multiple panels

References in corpus (41)

• Detection of Thermal Emission from an Extrasolar Planet
• TrES-1: The Transiting Planet of a Bright K0V Star
• Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres
• Improving Stellar and Planetary Parameters of Transiting Planet Systems: The Case of TrES-2
• WASP-1b and WASP-2b: Two new transiting exoplanets detected with SuperWASP and SOPHIE
• Theoretical Spectral Models of the Planet HD 209458b with a Thermal Inversion and Water Emission Bands
• HAT-P-1b: A Large-Radius, Low-Density Exoplanet Transiting one Member of a Stellar Binary
• Using Stellar Limb-Darkening to Refine the Properties of HD 209458b
• The phase-dependent Infrared brightness of the extrasolar planet upsilon Andromedae b
• WASP-3b: a strongly-irradiated transiting gas-giant planet
• Strong Infrared Emission from the Extrasolar Planet HD189733b
• The Transit Light Curve (TLC) Project. I. Four Consecutive Transits of the Exoplanet XO-1b
• A Spectrum of an Extrasolar Planet
• HD147506b: A Super-Massive Planet in an Eccentric Orbit Transiting a Bright Star
• Spitzer Transit and Secondary Eclipse Photometry of GJ 436b
• TrES-2: The First Transiting Planet in the Kepler Field
• XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary
• Theory for the Secondary Eclipse Fluxes, Spectra, Atmospheres, and Light Curves of Transiting Extrasolar Giant Planets
• A Transiting Planet of a Sun-like Star
• Accurate Spitzer infrared radius measurement for the hot Neptune GJ 436b
• Hot Nights on Extrasolar Planets: Mid-IR Phase Variations of Hot Jupiters
• HAT-P-3b: A heavy-element rich planet transiting a K dwarf star
• The Transit Light Curve Project. III. Tres Transits of TrES-1
• TrES-4: A Transiting Hot Jupiter of Very Low Density
• High accuracy transit photometry of the planet OGLE-TR-113b with a new deconvolution-based method
• The Transit Light Curve Project. VII. The Not-So-Bloated Exoplanet HAT-P-1b
• HAT-P-5b: A Jupiter-like hot Jupiter Transiting a Bright Star
• Characterization of the hot Neptune GJ 436b with Spitzer and ground-based observations
• HAT-P-6b: A Hot Jupiter transiting a bright F star
• Long-Period Objects in the Extrasolar Planetary Systems 47 UMa and 14 Her
• The Transit Light Curve (TLC) Project. II. Two Transits of the Exoplanet OGLE-TR-111b
• A Spitzer Search for Water in the Transiting Exoplanet HD189733b
• Refined parameters of the planet orbiting HD 189733
• The mid-infrared spectrum of the transiting exoplanet HD 209458b
• On the Age of Stars Harboring Transiting Planets
• WASP-1: A lithium- and metal-rich star with an oversized planet
• The transiting planet OGLE-TR-132b revisited with new spectroscopy and deconvolution photometry
• The `666' collaboration on OGLE transits: I. Accurate radius of the planets OGLE-TR-10b and OGLE-TR-56b with VLT deconvolution photometry
• K-band transit and secondary eclipse photometry of exoplanet OGLE-TR-113b
• Photometric follow-up of the transiting planet WASP-1b
• Chemical abundances for the transiting planet host stars OGLE-TR-10, 56, 111, 113, 132 and TrES-1. Abundances in different galactic populations

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• Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b
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• TiO and VO broad band absorption features in the optical spectrum of the atmosphere of the hot-Jupiter HD209458b
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• Thermal Emission of Exoplanet XO-1b
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• A lower radius and mass for the transiting extrasolar planet HAT-P-8b
• A Precise Estimate of the Radius of the Exoplanet HD 149026b from Spitzer Photometry
• On Signatures of Atmospheric Features in Thermal Phase Curves of Hot Jupiters
• The influence of non-isotropic scattering of thermal radiation on spectra of brown dwarfs and hot exoplanets
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