  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 (TTV) and Transit
Duration Variation (TDV) 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.
