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arXiv 2006.09657astro-ph.EP
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半人马座和巨行星交叉种群:起源和分布

Centaur and giant planet crossing populations: origin and distribution

Romina P. Di Sisto, Natalia L. Rossignoli

摘要:

目前的巨行星区域是一个过渡区,其中穿海王星天体(TNO)在成为木星家族彗星(JFC)的过程中交叉。它们的动力学行为受TNO的内在动力学特征以及与巨行星的相遇的影响。考虑到太阳系的当前配置,我们讨论了巨行星穿越(GPC)种群(具有$5.2$ au $ < q < 30$ au的天体),研究了它们的数量及其来源的演化。这一主题是回顾从以前的调查,也解决了新的数值模拟的动力学演化的散射盘对象(SDO)。我们得到了GPC的内禀轨道根数分布模型。分散盘代表了行星GPC和半人马座的主要来源,而来自冥王星的贡献比SD低一到两个数量级。我们从我们的模型中获得GPC的数量和大小分布,计算9600 GPC从SD与$D > 100$ km和$\sim 10^8$与$D > 1$ km在当前的人口。其他来源的贡献被认为微不足道。半人马座区域的平均寿命为720万年,而GPC区域的SDO的平均寿命为680万年。后者取决于初始倾角,即具有高倾角的那些,在GPC区中存活最长的那些。寿命与近日点距离也有相关性,其中更大的近日点导致更长的寿命。观测到的GPC的动力学演化是不同的逆行和逆行的对象。逆行GPCs的中位寿命低于逆行GPCs,因此经历了相对较快的进化。然而,这种更快的演化可能是由于大多数逆行GPC具有较低的近日点值,因此寿命较短。

英文摘要:

The current giant planet region is a transitional zone where transneptunian objects (TNOs) cross in their way to becoming Jupiter Family Comets (JFCs). Their dynamical behavior is conditioned by the intrinsic dynamical features of TNOs and also by the encounters with the giant planets. We address the Giant Planet Crossing (GPC) population (those objects with $5.2$ au $ < q < 30$ au) studying their number and their evolution from their sources, considering the current configuration of the Solar System. This subject is reviewed from previous investigations and also addressed by new numerical simulations of the dynamical evolution of Scattered Disk Objects (SDOs). We obtain a model of the intrinsic orbital element distribution of GPCs. The Scattered Disk represents the main source of prograde GPCs and Centaurs, while the contribution from Plutinos lies between one and two orders of magnitude below that from the SD. We obtain the number and size distribution of GPCs from our model, computing 9600 GPCs from the SD with $D > 100$ km and $\sim 10^8$ with $D > 1$ km in the current population. The contribution from other sources is considered negligible. The mean lifetime in the Centaur zone is 7.2 Myr, while the mean lifetime of SDOs in the GPC zone is of 68 Myr. The latter is dependent on the initial inclination, being the ones with high inclinations the ones that survive the longest in the GPC zone. There is also a correlation of lifetime with perihelion distance, where greater perihelion leads to longer lifetime. The dynamical evolution of observed GPCs is different for prograde and retrograde objects. Retrograde GPCs have lower median lifetime than prograde ones, thus experiencing a comparatively faster evolution. However, it is probable that this faster evolution is due to the fact that the majority of retrograde GPCs have low perihelion values and then, lower lifetimes.

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