Signatures of Obliquity in Thermal Phase Curves of Hot Jupiters

Abstract

Recent work suggests that many short-period extrasolar planets may have spin obliquities that are significantly tilted with respect to their orbital planes. These large obliquities are a natural outcome of ``secular spin-orbit resonance'', a configuration in which the planetary spin precession frequency matches the frequency of orbit nodal regression, or a Fourier component thereof. While exoplanet spin obliquities have not yet been measured directly, they may be detectable indirectly through their signatures in various observations, such as photometric measurements across the full phase of a planet's orbit. In this work, we employ a thermal radiative model to explore how large polar tilts affect full-phase light curves, and we discuss the range of unique signatures that are expected to result. We show that the well-studied short-period planets HD 149026 b, WASP-12 b, and CoRoT-2 b all exhibit phase curve features that may arise from being in high-obliquity states. We also constrain the parameters and assess the detectability of hypothetical perturbing planets that could maintain the planets in these states. Among the three planets considered, CoRoT-2 b has the tightest constraints on its proposed obliquity ($45.8^{\circ }\pm 1.4^{\circ }$) and axial orientation. For HD 149026 b, we find no significant evidence for a non-zero obliquity, and the phase curve of WASP-12 b is too complicated by strong tidal distortions for a conclusive assessment.

21 pages, 7 figures, 6 tables, accepted for publication in AJ

References in corpus (31)

• The NumPy array: a structure for efficient numerical computation
• Accurate, Empirical Radii and Masses of Planets and their Host Stars with Gaia Parallaxes
• Multi-Wavelength Constraints on the Day-Night Circulation Patterns of HD 189733b
• The Exoplanet Orbit Database II: Updates to exoplanets.org
• Near-UV Absorption, Chromospheric Activity, and Star-Planet Interactions in the WASP-12 system
• Atmospheric Dynamics of Hot Exoplanets
• The 4.5 $\mu$m full-orbit phase curve of the hot Jupiter HD 209458b
• Deciphering the Atmospheric Composition of WASP-12b: A Comprehensive Analysis of its Dayside Emission
• Tidal dissipation within hot Jupiters: a new appraisal
• Obliquity-Driven Sculpting of Exoplanetary Systems
• On the Origin of HD149026b
• Global Mapping of Earth-like Exoplanets from Scattered Light Curves
• Benchmarking the power of amateur observatories for TTV exoplanets detection
• Detection of a Westward Hotspot Offset in the Atmosphere of a Hot Gas Giant CoRoT-2b
• An analysis of the CoRoT-2 system: A young spotted star and its inflated giant planet
• Transit Photometry of the Core-Dominated Planet HD 149026b
• A New Model of Roche-lobe Overflow for Short-Period Gaseous Planets and Binary Stars
• Phase Offsets and the Energy Budgets of Hot Jupiters
• A Precise Estimate of the Radius of the Exoplanet HD 149026b from Spitzer Photometry
• Shallow-water Magnetohydrodynamics for Westward Hotspots on Hot Jupiters
• Excitation of Planetary Obliquities Through Planet-Disk Interactions
• Obliquity Tides May Drive WASP-12b's Rapid Orbital Decay
• Five New Transits of the Super-Neptune HD 149026
• Atmospheres on Nonsynchronized Eccentric-tilted Exoplanets I: Dynamical Regimes
• Atmospheres on Nonsynchronized Eccentric-tilted Exoplanets II: Thermal Light Curves
• Magnetic activity in the photosphere of CoRoT-Exo-2a. Active longitudes and short-term spot cycle in a young Sun-like star
• A Secular Resonant Origin for the Loneliness of Hot Jupiters
• Disentangling planetary and stellar activity features in the CoRoT-2 light curve
• The formation of HD 149026 b
• The Spin Effect on Planetary Radial Velocimetry of Exoplanets
• Aquaplanet Models on Eccentric Orbits: Effects of Rotation Rate on Observables

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• Thermal Phase Curves of XO-3b: an Eccentric Hot Jupiter at the Deuterium Burning Limit
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