Analyzing Exoplanet Phase Curve Information Content: Toward Optimized Observing Strategies

Abstract

Secondary eclipses and phase curves reveal information about the reflectivity and heat distribution in exoplanet atmospheres. The phase curve is composed of a combination of reflected, and thermally emitted light from the planet, and for circular orbits the phase curve peaks during the secondary eclipse or at an orbital phase of 0.5. Physical mechanisms have been discovered which shift the phase curve maximum of tidally locked close in planets to the right, or left, of the secondary eclipse. These mechanisms include cloud formations, and atmospheric superrotation, both of which serve to shift the thermally bright hot-spot, or highly reflective bright spot, of the atmosphere away from the sub-stellar point. Here we present a methodology for optimizing observing strategies for both secondary eclipses and phase curves with the goal of maximizing the information gained about the planetary atmosphere while minimizing the (assumed) continuous observation time. We show that we can increase the duty cycle of observations aimed at the measurements of phase curve characteristics (Amplitude, Phase offset) by up to $50\%$ for future platforms such as CHEOPS and JWST. We apply this methodology to the test cases of the Spitzer phase curve of 55-Cancri-e, which displays an eastward shift in its phase curve maximum, as well as model-generated observations of an ultra-short period planet observed with CHEOPS.

Accepted at The Astronomical Journal

References in corpus (33)

• MultiNest: an efficient and robust Bayesian inference tool for cosmology and particle physics
• Analytic Lightcurves for Planetary Transit Searches
• Multimodal nested sampling: an efficient and robust alternative to MCMC methods for astronomical data analysis
• Importance Nested Sampling and the MultiNest Algorithm
• A map of the day-night contrast of the extrasolar planet HD 189733b
• Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy
• A map of the large day-night temperature gradient of a super-Earth exoplanet
• Inference of Inhomogeneous Clouds in an Exoplanet Atmosphere
• CHEOPS: A Transit Photometry Mission for ESA's Small Mission Programme
• The phase-dependent Infrared brightness of the extrasolar planet upsilon Andromedae b
• Periodic Flux Variability of Stars due to the Reflex Doppler Effect Induced by Planetary Companions
• Detection of an atmosphere around the super-Earth 55 Cancri e
• Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry
• Photometric detection of non-transiting short-period low-mass companions through the beaming, ellipsoidal and reflection effects in Kepler and CoRoT lightcurves
• WASP-43b: The closest-orbiting hot Jupiter
• Optical Phase Curves of Kepler Exoplanets
• Understanding Trends Associated with Clouds in Irradiated Exoplanets
• A comprehensive study of Kepler phase curves and secondary eclipses -- temperatures and albedos of confirmed Kepler giant planets
• Atmospheric Characterization of the Hot Jupiter Kepler-13Ab
• Kepler-7b: A Transiting Planet with Unusually Low Density
• Detection Of KOI-13.01 Using The Photometric Orbit
• Ellipsoidal Oscillations Induced by Substellar Companions: A Prospect for the Kepler Mission
• The 55 Cancri Planetary System: Fully Self-Consistent N-body Constraints and a Dynamical Analysis
• Bayesian Evidence and Model Selection
• EXONEST: Bayesian Model Selection Applied to the Detection and Characterization of Exoplanets Via Photometric Variations
• The EVIL-MC Model for Ellipsoidal Variations of Planet-Hosting Stars and Applications to the HAT-P-7 System
• KELT-16b: A highly irradiated, ultra-short period hot Jupiter nearing tidal disruption
• Characterization of Kepler-91b and the Investigation of a Potential Trojan Companion Using EXONEST
• A massive exoplanet candidate around KOI-13: Independent confirmation by ellipsoidal variations
• Estimating transiting exoplanet masses from precise optical photometry
• Spitzer IRAC Sparsely Sampled Phase Curve of the Exoplanet WASP-14b
• Bayesian Methods for Analysis and Adaptive Scheduling of Exoplanet Observations
• Combining Photometry From Kepler and TESS to Improve Short-Period Exoplanet Characterization

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