111P/Helin–Roman–Crockett

Lore & Background

Comet Helin–Roman–Crockett was co-discovered by Eleanor and Ron Helin, Brian P. Roman and Randy L. Crockett on 5 January 1989 from images obtained about 1-2 days prior. It is known for making extremely close approaches to Jupiter, being a quasi-Hilda comet. During these approaches, it actually orbits Jupiter. The last such approach was in 1976, the next will be in 2071. The Jovian orbits are highly elliptical and subject to intense Solar perturbation at apojove, which eventually pulls the comet out of Jovian orbit for the cycle to begin anew.

Simulations predict such a cycle is unstable; the object will either be captured into an encounter orbit (e.g., Shoemaker-Levy 9) or expelled into a new orbit which does not have periodic approaches. This implies that 111P's orbit is recent within the past few thousand years. Estimates for the size of its nucleus in 2004 place it roughly about 1.2 km in diameter. Follow-up studies in 2007 generally agree with this estimate, and depending on the comet's activity, the comet is likely somewhere between 0.92–2.78 km in diameter.

Reader's Guide

111P/Helin–Roman–Crockett is significant as an Encke-type comet that exhibits a rare dynamical behavior: it makes extremely close approaches to Jupiter and temporarily enters Jovian orbit as a quasi-Hilda comet. The article describes that during these approaches, the comet actually orbits Jupiter, with the last such event in 1976 and the next predicted for 2071. The Jovian orbits are highly elliptical and subject to intense Solar perturbation at apojove, which eventually pulls the comet out of Jovian orbit, restarting the cycle. Simulations indicate this cycle is unstable, leading to two possible fates: capture into an encounter orbit similar to Shoemaker-Levy 9, or expulsion into a new orbit without periodic approaches. This instability implies that the comet's current orbit is recent, within the past few thousand years. The comet's nucleus size estimates from 2004 and 2007 provide a range of 0.92–2.78 km in diameter, with a central value of about 1.2 km, though the exact size depends on the comet's activity level. These characteristics make 111P a valuable object for studying cometary dynamics and interactions with giant planets.

Did You Know?

• 111P/Helin–Roman–Crockett is an Encke-type comet with an 8.46-year orbit.
• The comet makes extremely close approaches to Jupiter and temporarily orbits the planet.
• Its nucleus diameter is estimated between 0.92 and 2.78 km, depending on activity.