Cronomoons: origin, dynamics, and light-curve features of ringed exomoons

Mario Sucerquia*, Jaime A. Alvarado-Montes*, Amelia Bayo, Jorge Cuadra, Nicolás Cuello, Cristian Giuppone, Matías Montesinos, J. Olofsson, Christian Schwab, Lee Spitler, Jorge I. Zuluaga

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


In recent years, technical and theoretical work to detect moons and rings around exoplanets has been attempted. The small mass/size ratios between moons and planets means this is very challenging, having only one exoplanetary system where spotting an exomoon might be feasible (i.e. Kepler-1625b i). In this work, we study the dynamical evolution of ringed exomoons, dubbed cronomoons after their similarity with Cronus (Greek for Saturn), and after Chronos (the epitome of time), following the Transit Timing Variations and Transit Duration Variation that they produce on their host planet. Cronomoons have extended systems of rings that make them appear bigger than they actually are when transiting in front of their host star. We explore different possible scenarios that could lead to the formation of such circumsatellital rings, and through the study of the dynamical/thermodynamic stability and lifespan of their dust and ice ring particles, we found that an isolated cronomoon can survive for time-scales long enough to be detected and followed up. If these objects exist, cronomoons’ rings will exhibit gaps similar to Saturn’s Cassini Division and analogous to the asteroid belt’s Kirkwood gaps but instead raised due to resonances induced by the host planet. Finally, we analyse the case of Kepler-1625b i under the scope of this work, finding that the controversial giant moon could instead be an Earth-mass cronomoon. From a theoretical perspective, this scenario can contribute to a better interpretation of the underlying phenomenology in current and future observations.
Original languageEnglish
Pages (from-to)1032-1044
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - May 2022


  • methods: analytical
  • techniques: photometric
  • planets and satellites: detection
  • planets and satellites: dynamical evolution and stability
  • planets and satellites: rings


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