Rutgers University Astrophysics Seminar

Triton, seventh largest satellite in the Solar System, orbits Neptune in a direction opposite the planet's spin. This peculiarity, unique amongst large satellites, points to a capture origin. Two plausible theories were advanced around the time of the Voyager flybys to explain how Neptune might have snared Triton, but both require some fine tuning. Recently Craig Agnor and I have proposed a new scenario in which Neptune captures Triton from an originally heliocentric Pluto-Charon type binary. In the aftermath of this event, the original satellites of Neptune were destroyed, and most of the debris was accreted onto Triton. Over the next 100 million years, the satellite's orbit was circularized by tides raised on it by the planet, and a stunted group of new moonlets grew from the remaining rubble. Periodically during the subsequent history of the system, Triton has exerted considerable influence on these small inner satellites via three-body resonances that have elongated and tilted the moonlet orbits. In this talk I will trace the orbital history of Neptune's satellite system from Triton's dramatic capture to the present day.