Constraining Hot Jupiter Atmospheric Structure and Dynamics through Doppler Shifted Emission Spectra

Abstract

We present a coupled 3-D atmospheric dynamics and radiative transfer model to predict the disk-integrated thermal emission spectra of transiting exoplanets in edge-on orbits. We calculate spectra at high resolution to examine the extent to which high-resolution emission spectra are influenced by 3-D atmospheric dynamics and planetary rotation, and to determine whether and how we can constrain thermal structures and atmospheric dynamics through high-resolution spectroscopy. This study represents the first time that the line-of-sight geometry and resulting Doppler shifts from winds and rotation have been treated self-consistently in an emission spectrum radiative transfer model, which allow us to assess the impact of the velocity field on thermal emission spectra. We apply our model to predict emission spectra as a function of orbital phase for three hot Jupiters, HD 209458b, WASP-43b and HD 189733b. We find net Doppler shifts in modeled spectra due to a combination of winds and rotation at a level of 1-3 km/s. These Doppler signatures vary in a quasi-sinusoidal pattern over the course of the planets' orbits as the hot spots approach and recede from the observer's viewpoint. We predict that WASP-43b produces the largest Doppler shift due to its fast rotation rate. We find that the net Doppler shift in an exoplanet's disk-integrated thermal emission spectrum results from a complex combination of winds, rotation, and thermal structure. However, we offer a simple method that estimates the magnitude of equatorial wind speeds in hot Jupiters through measurements of net Doppler shifts and lower resolution thermal phase curves.

18 pages, 1 table, 7 figures, accepted for publication in ApJ

References in corpus (20)

• On the radiative equilibrium of irradiated planetary atmospheres
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• The fast spin-rotation of a young extrasolar planet
• A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b
• Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy
• The Broadband Infrared Emission Spectrum of the Exoplanet HD 189733b
• Multi-Wavelength Constraints on the Day-Night Circulation Patterns of HD 189733b
• Dynamics and Disequilibrium Carbon Chemistry in Hot Jupiter Atmospheres, With Application to HD 209458b
• The Very Low Albedo of an Extrasolar Planet: MOST Spacebased Photometry of HD 209458
• Carbon monoxide and water vapor in the atmosphere of the non-transiting exoplanet HD 179949 b
• Spitzer Phase Curve Constraints for WASP-43b at 3.6 and 4.5 microns
• Weighing The Non-Transiting Hot Jupiter Tau BOO b
• The Atmospheric Circulation of the Hot Jupiter WASP-43b: Comparing Three-Dimensional Models to Spectrophotometric Data
• The 4.5 $\mu$m full-orbit phase curve of the hot Jupiter HD 209458b
• New Analysis Indicates No Thermal Inversion in the Atmosphere of HD 209458b
• The Impact of Non-Uniform Thermal Structure on the Interpretation of Exoplanet Emission Spectra
• Water vapor in the spectrum of the extrasolar planet HD 189733b: 2. The eclipse
• Evidence against a strong thermal inversion in HD 209458 b from high-dispersion spectroscopy
• A Spitzer Infrared Radius for the Transiting Extrasolar Planet HD209458b
• Evidence for the Direct Detection of the Thermal Spectrum of the Non-Transiting Hot Gas Giant HD 88133 b