目前在太陽系中許多存在小天體的區域皆存在著雙星系統。而這些雙星系統其各種性質更能夠提供建構該區域演化過程的限制條件。其中位於古柏帶的海王星外雙星系統中，特別是屬於傳統型冷群海王星外天體的雙星系統，其成員間相近的質量比、分布極廣的離心率、較高的大軌道比率及相近的順向與逆向軌道比，無法僅用現有的形成理論來解釋它們的存在。而目前針對它們的演化至今討論不多。在此我們探討於海王星外雙星系統形成之後其與海王星外天體彼此之間重力交互作用過程，並以海王星外雙星系統為例測試雙微行星的碰撞截面積，來解釋我們的結果。我們的結果顯示即便於高速( )的環境下雙微行星的碰撞截面積仍舊比單獨兩顆微行星碰撞截面積來得高，並且碰撞截面積與雙星的軌道半長軸具有正相關的關係。另外我們也發現高離心率( )、半長軸較大( )的海王星外雙星系統的存活率偏低，即使存活其軌道參數也易受海王星外天體的重力影響；低離心率( )、半長軸較小( )的海王星雙星系統則反之。根據我們的結果，我們認為低離心率、半長軸較小的海王星外雙星系統其演化過程可能以潮汐圓化過程為主導，而海王星外天體的遭遇事件可能主導高離心率、半長軸較大的海王星外雙星系統其演化過程。最後，我們建議未來探討海王星外雙星系統的各項特徵時，應該針對潮汐作用過程和遭遇事件發生的頻率進行較細部的研究。Many binary asteroids distribute at different regions in the solar system. Theirproperties provide the restrictive condition to construct evolution model in differentregions. The trans-Neptunian binary (TNB), especially, being classified the dynamicalcold Kuiper belt object, cannot explain their existence by various formation theoriesbecause their near-equal mass ratio, wide distributed eccentricity, higher large orbitratio, and near-equal prograde to retrograde orbit ratio. But their evolution is rarediscussed. We study gravitational interaction between TNBs and trans-Neptunianobjects (TNOs) after TNBs formed. We also test the collisional cross section of binaryplanetesimals (BPs) to explain our results. Our results show the binary-singlecollisional cross section is larger than the single-single collision even if the relativevelocity is high ( ), and the binary-single collisional cross sectiondepend on the semi-major axis of binary. We also find out that TNBs with the higheccentric ( ) and larger semi-major axis ( ) are not easy to survival.Their orbits are changed easily even if they survive after the TNOs close encounter,vice versa. Follow our results, we think the low eccentric and small orbital TNBs aredominated by tidal evolution and the evolution of higher eccentric and large orbitalTNBs are dominated by the close encounter with TNOs. In future, about studying theproperties of TNBs, we suggest that tidal evolution and frequency of the closeencounter events should be considered in detail.
