Abstract
Comets are icy objects that orbitally evolve from the trans-Neptunian region into the inner solar system, where they are heated by solar radiation and become active due to the sublimation of water ice. Here we perform simulations in which cometary reservoirs are formed in the early solar system and evolved over 4.5 Gyr.
The gravitational effects of Planet. 9 (P9) are included in some simulations. Different models are considered for comets to be active, including a simple assumption that comets remain active for N-p(q) perihelion passages with perihelion distance q 1000 is required to obtain a steady-state population of large active HTCs that is consistent with observations.
To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that N-p(2.5) less than or similar to 10, possibly because the detected long-period comets are smaller and much easier to disrupt than observed HTCs.