Orbital Alignment of Main-Belt Comets

TL;DR

This study analyzes the orbital elements of main-belt comets, revealing their alignment with Jupiter and suggesting that their current orbital states may influence their activity, providing insights into the distribution of ice in the inner solar system.

Contribution

It uncovers the orbital alignment and eccentricity excitation of MBCs, linking their activity to current orbital conditions influenced by Jupiter.

Findings

MBCs have similar longitudes of perihelion aligned with Jupiter.

Current osculating eccentricities are higher than proper eccentricities.

Orbital conditions favorable for activity are transient and influenced by Jupiter.

Abstract

We examine the orbital element distribution of main-belt comets (MBCs), which are objects that exhibit cometary activity yet orbit in the main asteroid belt, and may be potentially useful as tracers of ice in the inner solar system. We find that the currently known and currently active MBCs have remarkably similar longitudes of perihelion, which are also aligned with that of Jupiter. The clustered objects have significantly higher current osculating eccentricities relative to their proper eccentricities, consistent with their orbits being currently, though only temporarily, secularly excited in osculating eccentricity due to Jupiter's influence. At the moment, most MBCs seem to have current osculating elements that may be particularly favorable for the object becoming active (e.g., maybe because of higher perihelion temperatures or higher impact velocities causing an effective increase in the size of the potential triggering impactor population). At other times, other icy asteroids will have those favorable conditions and might become MBCs at those times as well.