1981/11/01 by J. G. Hills · 17 citations
Physics and Astronomy · #Astro and Planetary Science #Planetary Science and Exploration #Stellar, planetary, and galactic studies
paper · doi:10.1086/113058
openalex publication_date 1981/11/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/04/21
The theoretically-determined location of the boundary between semimajor axes of those comets entering the planetary system only in bursts or showers, and those which arrive in a steady stream, is abrupt and falls at the observed inner edge of the Oort cloud. It is proposed that the comets were formed in the outer parts of the collapsing protosun, which had a radius of less than 5000 AU. If so, then: (1) a first-generation comet cloud may have been produced, with a radius of more than 1000 AU, and the coupled dynamical perturbations of passing stars and Jupiter would lead to the formation of a comet cloud similar to the Oort; while (2) if the Oort cloud comets originated in this inner cloud, and were later ejected into their present orbits by the perturbations of passing stars and Jupiter, the total inner cloud mass is two orders of magnitude greater than that of the Oort cloud.