The Neptune Trojans

Leading and trailing Neptune in its orbit around the Sun are two swarms of small worlds called Trojans. Neptune’s Trojans were likely captured from the disk that Neptune migrated through during the early evolution of the outer solar system, and their current properties can reveal properties of that primordial disk and how Neptune interacted with it.

In 2011 I serendipitously discovered and characterized the L5 Neptune Trojan 2011 HM102, which is the highest-inclination stable Neptune Trojan known as well as the largest L5 Trojan object known in the entire solar system. The extreme orbit of 2011 HM102 prompted me to characterize the overall distribution of Neptune Trojan orbits, which required developing new survey-agnostic statistical characterization techniques to remove discovery biases present in the sample of known Neptune Trojans.

Using these new statistical techniques, I produced the first quantitative measure of the intrinsic orbit distribution of the Neptune Trojans, confirming that they are a very dynamically-excited population. Using a large series of numerical n-body simulations, I demonstrated that if Neptune migrated as quickly as some models suggest, the bodies that became Neptune Trojans must have been pre-excited before Neptune's arrival. Subsequent work by other researchers has found that very slow Neptune migration could also result in a very excited Neptune Trojan population.