The end states of long-period comets and the origin of Halley-type comets

Abstract

We analyze a sample of 73 old long-period comets (LPCs) (orbital periods $200<P<1000$ yr) with perihelion distances $q<2.5$ au, discovered in the period 1850-2014. We cloned the observed comets and also added fictitious LPCs with perihelia in the Jupiter's zone. We consider both a purely dynamical evolution and a physico-dynamical one with different physical lifetimes. We can fit the computed energy distribution of comets with $q<1.3$ au to the observed one only within the energy range $0.01<x<0.04$ au${}^{-1}$ (or periods $125<P<1000$ yr), where the "energy" is taken as the inverse of the semimajor axis $a$, namely $x\equiv 1/a$. The best results are obtained for physical lifetimes of about 200-300 revolutions (for a comet with a standard $q=1$ au). We find that neither a purely dynamical evolution, nor a physico-dynamical one can reproduce the long tail of larger binding energies ($x \gsim 0.04$ au${}^{-1}$) that correspond to most Halley-type comets (HTCs) and Jupiter-family comets. We conclude that most HTCs are not the end states of the evolution of LPCs, but come from a different source, a flattened one that we identify with the Centaurs that are scattered to the inner planetary region from the trans-Neptunian belt. These results also show that the boundary between LPCs and HTCs should be located at an energy $x\sim 0.04$ au${}^{-1}$ ($P\sim 125$ yr), rather than the conventional classical boundary at $P=200$ yr.

34 pages, 17 figures, article in press

References in corpus (3)

• The Active Centaurs
• Cometary masses derived from non-gravitational forces
• Resonance capture at arbitrary inclination

Cited by in corpus (8)

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• Dynamical evolution and end states of active and inactive Centaurs
• Strength, stability and three dimensional structure of mean motion resonances in the Solar System
• Resonance capture at arbitrary inclination: II. Effect of the radial drift rate
• Centaurs potentially in retrograde co-orbit resonance with Saturn
• Orbital stability in the Solar System for arbitrary inclinations and eccentricities: planetary perturbations versus resonances
• Resonances in the asteroid and trans-Neptunian belts: a brief review
• Orbit injection of planet-crossing asteroids