Leveraging photometry for deconfusion of directly imaged multiplanet systems

Future missions, including the Habitable Worlds Observatory, will aim to image Earth-like exoplanets around Sun-like stars in reflected light. Determining whether an exoplanet is in the habitable zone of its star may be difficult in multiplanet systems when the observer does not know in advance which detection corresponds to which planet. This “confusion” problem will be a concern for future missions due to the high occurrence rate of multiplanet systems and will be exacerbated by the lack of prior knowledge about planets’ orbital parameters or characteristics. We address the exoplanet confusion problem by applying a photometry model to update an orbit ranking scheme for a “deconfuser” tool. This helps to account for the phase variation of planets throughout their orbits. We demonstrate the updated ranking scheme as a proof-of-concept on a subset of known to be confused simulated multiplanet systems among three inclination groupings (i.e., low, medium, and high). We find that incorporating photometry improves correctly interpreting previously confused orbits in more than half of these particularly challenging cases. These results emphasize that photometry is useful for orbit discrimination and deconfusion of directly imaged multiplanet systems, providing a framework for including photometry alongside astrometry when fitting orbits to detections.