The Evolution Of Centaurs And Formation Of Potentially Hazardous Objects

Centaurs are objects whose orbits are mainly between Jupiter and Neptune.Recent research has shown that Centaurs may reach the Earth's vicinity,that is,they become Near Earth Objects(NEOs),which have great influence on Earth.Among NEOs,the most hazardous are those so-called potentially hazardous objects(PHOs).Therefore,it is quite meaningful to have a research on the evolutionary process of Centaurs becoming NEOs and PHOs.In this paper,we numerically integrate the clones of 214 Centaurs discovered so far to study the possibility of Centaurs becoming NEOs.We find that 12.68%Centaurs become NEOs after the entire integration that lasts 10 million years and that NEOs can be divided into two categories:Near-Earth Jupiter Family comets(NEJFCs)and Damocloids,according to the orbital characteristics when they first reach Earth's vicinity(perihelion distance q<1.3AU).Based on the NEOs we obtain,we further study the possibility of NEOs becoming PHOs and the stability of PHOs.We find that the time of Damocloids remaining on PHOs' orbits is much longer than NEJFCs and the minimum orbit intersection distance(MOID)between Damocloids and Earth can be smaller than NEJFCs,which increase the long-term threat of Damocloids to Earth.We also find that the MOIDs between some PHOs and Earth become quite small abruptly,while orbital parameters don't change obviously,which may means that these PHOs may have great threat to Earth.