LUNA: An algorithm for generating dynamic planet-moon transits

TL;DR

LUNA is a new algorithm that simulates detailed transit light curves of planet-moon systems, including dynamical effects and light curve features, aiding in the detection of exomoons with Kepler data.

Contribution

The paper introduces LUNA, an analytical algorithm that models transit light curves of planet-moon systems with dynamical and light curve effects, enhancing exomoon detection capabilities.

Findings

LUNA can generate realistic transit light curves including moon signals.

Feasibility demonstrated for detecting Earth-like moons around Neptune-like planets.

Potential to identify prograde and retrograde moons with Kepler data.

Abstract

It has been previously shown that moons of extrasolar planets may be detectable with the Kepler Mission, for moon masses above ~0.2 Earth masses Kipping et al. 2009c. Transit timing effects have been formerly identified as a potent tool to this end, exploiting the dynamics of the system. In this work, we explore the simulation of transit light curves of a planet plus a single moon including not only the transit timing effects but also the light curve signal of the moon itself. We introduce our new algorithm, LUNA, which produces transit light curves for both bodies, analytically accounting for shadow overlaps, stellar limb darkening and planet-moon dynamical motion. By building the dynamics into the core of LUNA, the routine automatically accounts for transit timing/duration variations and ingress/egress asymmetries for not only the planet, but also the moon. We then generate some artificial data for two feasibly detectable hypothetical systems of interest: a i) prograde and ii) retrograde Earth-like moon around a habitable-zone Neptune for a M-dwarf system. We fit the hypothetical systems using LUNA and demonstrate the feasibility of detecting these cases with Kepler photometry.