Abstract
Long-period (LP) comets, Halley-type (HT) comets, and even some comets of the Jupiter family, probably come from the Oort cloud, a huge reservoir of icy bodies that surrounds the solar system. Therefore, these comets become important probes to learn about the distant Oort cloud population. We review the fundamental dynamical properties of LP comets, and what is our current understanding of the dynamical mechanisms that bring these bodies from the distant Oort cloud region to the inner planetary region. Most new comets have original reciprocal semimajor axes in the range2 × 10-5 < 1/aorig < 5 × 10-5AU-1. Yet, this cannot be taken to represent the actual space distribution of Oort cloud comets, but only the region in the energy space in which external perturbers have the greatest efficiency in bringing comets to the inner planetary region. The flux of Oort cloud comets in the outer planetary region is found to be at least several tens times greater than the flux in the inner planetary region. The sharp decrease closer to the Sun is due to the powerful gravitational fields of Jupiter and Saturn that prevent most Oort cloud comets from reaching the Earth’s neighborhood (they act as a dynamical barrier). A small fraction of ∼10-2 Oort cloud comets become Halley type (orbital periods P < 200 yr), and some of them can reach short-period orbits with P < 20 yr. We analyze whether we can distinguish the latter, very ‘old” LP comets, from comets of the Jupier family coming from the Edgeworth-Kuiper belt.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Bailey, M. E.: 1983, Mon. Not. Roy. Astron. Soc. 204, 603-633.
Bailey, M. E., Chambers, J. E., and Hahn, G.: 1992, Astron. Astrophys. 257, 315-322.
Biermann, L.: 1978, in A. Reiz and T. Anderson (eds.), Astronomical Papers Dedicated to Bengt Stromgren, Copenhagen Observatory, p. 327.
Delsemme, A. H.: 1978, Astron. Astrophys. 187, 913-918.
Duncan, M., Quinn, T., and Tremaine, S.: 1988, Astrophys. J. Lett. 328, L69-L73.
Dybczynski, P. A.: 2002, Astron. Astrophys., in press.
Everhart, E.: 1976, in B. Donn, M. Mumma, W. Jackson, M. A'Hearn, and R. Harrington (eds.), The Study of Comets, IAU Coll. 25, NASA SP-393, pp. 445-464.
Fernández, J. A.: 1980, Mon. Not. Roy. Astron. Soc. 192, 481-491.
Fernández, J. A.: 1981, Astron. Astrophys. 96, 26-35.
Fernández, J. A.: 1992, in S. Ferraz-Mello (ed.), Chaos, Resonance and Collective Dynamical Phenomena in the Solar System, IAU Symp. No. 152, pp. 239-254, Kluwer Academic Publishers, Dordrecht.
Fernández, J. A.: 1994, in A. Milani et al. (eds.), Asteroids, Comets,Meteors 1993, Kluwer Academic Publishers, Dordrecht, pp. 223-240.
Fernández, J. A.: 1997, Icarus 129, 106-119.
Fernández, J. A. and Gallardo, T.: 1994, Astron. Astrophys. 281, 911-922.
Fernández, J. A. and Gallardo, T.: 1999, in J. Svoreň, E.M. Pittich, and H. Rickman (eds.), Evolution and Source Regions of Asteroids and Comets, Astr. Inst. Slovak Acad. Sci., Tatranská Lomnica, pp. 327-338.
Fernández, J. A. and Ip, W.-H.: 1991, in R. L. Newburn, M. Neugebauer, and J. Rahe (eds.), Comets in the Post-Halley Era, IAU Coll. No. 121, Kluwer Academic Publishers, Netherlands, pp. 487-535.
Hills, J. G.: 1981, Astron. J. 86, 1730-1740.
Hut, P. and Tremaine, S.: 1985, Astron. J. 90, 1548-1557.
Kresák, L.: 1992, Astron. Astrophys. 259, 682-691.
Marsden, B. G. and Williams, G. V.: 1999, ‘Catalogue of Cometary Orbits’, 13th edn., Minor Planet Center, IAU.
Oort, J. H.: 1950, Bull. Astron. Inst. Neth. 11, 91-110.
Öpik, E. J.: 1932, Proc. Am. Acad. Arts Sci. 67, 1659-1683.
Torbett, M. V.: 1986, Mon. Not. Roy. Astron. Soc. 223, 885-895.
Weissman, P. R.: 1985, in A. Carusi and G. B. Valsecchi (eds.), Dynamics of Comets: Their Origin and Evolution, Reidel, Dordrecht, pp. 87-96.
Yabushita, S. and Tsujii, T.: 1991, Mon. Not. Roy. Astron. Soc. 252, 151-155.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Fernández, J.A. Long-Period Comets and the Oort Cloud. Earth, Moon, and Planets 89, 325–343 (2000). https://doi.org/10.1023/A:1021571108658
Issue Date:
DOI: https://doi.org/10.1023/A:1021571108658