Shadow Imaging of Transiting Objects

The light curves of transiting exoplanets are rich in information. If we assume a physical model for an exoplanet---usually, a spherical body in a Keplerian orbit about a host star---we may then infer the parameters of this model, including physical properties of the planet, its orbit, and the host star, directly from the light curve. However, anomalous transit-like events, such as those observed in star KIC 8462852 (Boyajian et al. 2016), resist this type of analysis, because their physical cause, and consequently the appropriate model, is not apparent. Here, we present a novel approach to modeling the shape of a transiting object from its light curve alone, in which we assume no physical model for the object. We instead model the object as a grid of pixels which transits the star; each pixel has an opacity, ranging from transparent to opaque. We infer these opacities directly from the light curve using the Simultaneous Algebraic Reconstruction Technique (Andersen & Kak 1984), an algorithm developed for medical tomographic imaging, and thus generate an image of the transiting object.