From Wikipedia, the free encyclopedia
Discovered byEleanor F. Helin
Ron Helin
Brian P. Roman
Randy L. Crockett
Palomar Observatory (675)
Discovery dateJanuary 5, 1989
1988 XIII
Orbital characteristics
EpochMarch 6, 2006
Aphelion4.607 AU
Perihelion3.474 AU
Semi-major axis4.041 AU
Orbital period8.122 a
Last perihelionJune 15, 2021[1]
January 30, 2013[2]
December 27, 2004[3]
Next perihelion2029-Dec-09[4]

111P/Helin–Roman–Crockett is a periodic comet in the Solar System. It was discovered by Eleanor and Ron Helin on 5 January 1989 from images obtained on the 3rd and 4th of that month. It is a Jupiter family comet known for extremely close approaches to Jupiter being a Quasi-Hilda comet. During these approaches, it actually orbits Jupiter.[5] The last such approach was in 1976,[6] the next will be in 2071.[6] 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. It fits the definition of an Encke-type comet with (TJupiter > 3; a < aJupiter).[7]


  1. ^ "111P/Helin-Roman-Crockett Orbit". Minor Planet Center. Retrieved 2014-06-17.
  2. ^ Syuichi Nakano (2005-10-26). "111P/Helin-Roman-Crockett (NK 1271)". OAA Computing and Minor Planet Sections. Retrieved 2012-02-24.
  3. ^ Seiichi Yoshida (2011-07-22). "111P/Helin-Roman-Crockett". Seiichi Yoshida's Comet Catalog. Retrieved 2012-02-24.
  4. ^ "Horizons Batch for 111P/Helin-Roman-Crockett on 2029-Dec-09" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 2021-09-12. (JPL#8/Soln.date: 2013-Jan-28)
  5. ^ Tancredi, G. (1990). "The capture of P/Helin-Roman-Crockett by Jupiter". Comptes-rendus de la table ronde: nouveaux développements en planétologie dynamique. Nouveaux Développements en Planétologie Dynamique. pp. 273–279. Bibcode:1990ndpd.conf..273T.
  6. ^ a b "JPL Close-Approach Data: 111P/Helin-Roman-Crockett" (2001-09-20 last obs). Retrieved 2012-02-24.
  7. ^ "JPL Small-Body Database Browser: 111P/Helin-Roman-Crockett" (2001-09-20 last obs). Jet Propulsion Laboratory. Retrieved 2012-07-26.

External links[edit]

Numbered comets
111P/Helin–Roman–Crockett Next