The detectability of extrasolar planet surroundings - I. Reflected-light photometry of unresolved rings

TL;DR

This paper investigates how the reflected visible light from unresolved ringed extrasolar planets varies with orbital phase, proposing that photometric signatures can reveal the presence of rings.

Contribution

It introduces a simple model to identify photometric signatures of rings around unresolved extrasolar planets, aiding future detection efforts.

Findings

Ringed planets exhibit distinct photometric variations with phase angle.

Photometric signatures can indicate the presence of rings even when unresolved.

Model provides a basis for interpreting future high-contrast imaging data.

Abstract

It is expected that the next generation of high-contrast imaging instruments will deliver the first unresolved image of an extrasolar planet. The emitted thermal infrared light from the planet should show no phase effect assuming the planet is in thermal equilibrium. But the reflected visible light will vary versus the phase angle. Here, we study the photometric variation of the reflected light versus the orbital phase of a ringed extrasolar planet. We show that a ring around an extrasolar planet, both obviously unresolved, can be detected by its specific photometric signature. A simple quantitative model is discussed, taking into account the basic optical and geometrical properties of the ringed planet.