Consequences of dynamically unstable moons in extrasolar systems

Moons orbiting rocky exoplanets in compact orbits about other stars experience an accelerated tidal evolution, and can either merge with their parent planet or reach the limit of dynamical instability within a Hubble time. We review parameter space over which moons become unbound, including effects atmospheric tides on planetary spin. find that such change final outcome from merger to escape, albeit limited space. also follow further evolution unbound moons, demonstrate overwhelmingly most likely long-term is moon returns collide its original planet. The dust released by collision estimated optical depths approximately 0.001, exhibit characteristic temperatures few hundred degrees Kelvin, last for thousand years. These properties make events attractive model emerging class middle-aged main sequence are observed show transient clouds warm dust. Furthermore, late between returning hyperbolic orbit may sterilise otherwise habitable