P/2019 LD2 (ATLAS): An Active Centaur in Imminent Transition to the Jupiter Family

TL;DR

This study uses dynamical simulations to analyze the orbital history and thermal environment of active Centaur P/2019 LD2, revealing its recent transition towards becoming a Jupiter Family Comet and providing insights into its physical state.

Contribution

It is the first to model the orbital evolution and transition timing of P/2019 LD2 as it moves from the Centaur to Jupiter Family Comet population.

Findings

P/2019 LD2 is near a dynamical 'Gateway' facilitating transitions to JFCs.

It likely has a relatively pristine nucleus due to limited inner solar system exposure.

Transition to JFC expected around 2063, allowing observation of this evolutionary process.

Abstract

The recently discovered object P/2019 LD2 (ATLAS) was initially thought to be a Jupiter Trojan asteroid, until dynamical studies and the appearance of persistent cometary activity revealed that this object is actually an active Centaur. However, the dynamical history, thermal environment, and impact of such environments on the activity of 2019 LD2 are poorly understood. Here we conduct dynamical simulations to constrain its orbital history and resulting thermal environment over the past 3000 years. We find that 2019 LD2 is currently in the vicinity of a dynamical "Gateway" that facilitates the majority of transitions from the Centaur population into the Jupiter Family of Comets (JFC population; Sarid et al. 2019). Our calculations show that it is unlikely to have spent significant amounts of time in the inner solar system, suggesting that its nucleus is relatively pristine in terms of physical, chemical, and thermal processing through its history. This could explain its relatively high level of distant activity as a recently activated primordial body. Finally, we find that the median frequency of transition from the Gateway population into the JFC population varies from once every ~3 years to less than once every 70 years, if 2019 LD2's nucleus is ~1 km in radius or greater than 3 km in radius. Forward modeling of 2019 LD2 shows that it will transition into the JFC population in 2063, representing the first known opportunity to observe the evolution of an active Centaur nucleus as it experiences this population-defining transition.