LUNA: an algorithm for generating dynamic planet-moon transits

It has been previously shown that moons of extrasolar planets may be detectable with the Kepler Mission, for moon masses above similar to 0.2M(circle dot). 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 transittiming/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: (i) prograde and (ii) retrograde Earth-like moons around a habitable-zone Neptune for an M dwarf system. We fit the hypothetical systems using LUNA and demonstrate the feasibility of detecting these cases with Kepler photometry.