That's no moon: Exomoon survival and detection limitations

RESUMO

While moons are ubiquitous in the Solar System, exomoons have not yet been unambiguously confirmed despite the discov- ery of over 5,600 exoplanets. We investigated the reasons for this lack of detections by reviewing high-impact literature searches, assessing dynamical stability and detectability constraints, and comparing these with the moon population in the Solar System. We compiled a homogeneous catalogue of 24 proposed exomoon candidates, including stellar, planetary, and inferred lunar parameters. For each case we applied Hill, Roche, and Laplace stability criteria and estimated detectability limits for current and forth- coming instruments. In addition, we tested 6038 confirmed exoplanets against the same stability and mission-specific observational filters for a given range of moon parameters. A large fraction of the potential exomoon candidates investigated in the literature are either inconsistent with long-term stability or produce signals below Kepler sensitivity. Only 8 of the 13 candidates meet at least one of the stability criteria. Our extended analysis highlights 27 promising targets for exomoon searches with PLATO, while moons with Solar-System-like properties remain below current thresholds. The lack of exomoon detections is likely due to a combination of the inefficient formation of stable massive moons and limited instrumental sensitivity. Other processes, such as early moon loss during planetary migration or giant impacts, may also influence moon survival. Future searches should prioritise systems that combine long-term dynamical stability with favourable observational conditions for next-generation photometric and astrometric facilities.