Planetary Phase Variations of the 55 Cancri System

TL;DR

This paper models the optical phase variations of the 55 Cancri exoplanet system to explore how different surface and atmospheric properties influence observable signals, aiding future characterization efforts.

Contribution

It introduces detailed photometric phase curve models for 55 Cancri e, assessing how surface and atmospheric assumptions affect observable phase variations.

Findings

Large differences in geometric albedo can distinguish surface models.

Scattering phase function cannot be constrained with foreseeable data.

Planet b significantly influences phase variations depending on planet e's surface.

Abstract

Characterization of the composition, surface properties, and atmospheric conditions of exoplanets is a rapidly progressing field as the data to study such aspects become more accessible. Bright targets, such as the multi-planet 55 Cancri system, allow an opportunity to achieve high signal-to-noise for the detection of photometric phase variations to constrain the planetary albedos. The recent discovery that that inner-most planet, 55 Cancri e, transits the host star introduces new prospects for studying this system. Here we calculate photometric phase curves at optical wavelengths for the system with varying assumptions for the surface and atmospheric properties of 55 Cancri e. We show that the large differences in geometric albedo allows one to distinguish between various surface models, that the scattering phase function cannot be constrained with foreseeable data, and that planet b will contribute significantly to the phase variation depending upon the surface of planet e. We discuss detection limits and how these models may be used with future instrumentation to further characterize these planets and distinguish between various assumptions regarding surface conditions.