The fundamental role of the Oort cloud in determining the flux of comets through the planetary system
The fundamental role of the Oort cloud in determining the flux of comets through the planetary system
复制标题
奥尔特云在确定彗星通过行星系统的通量方面的基本作用
DOI：
10.1111/j.1365-2966.2007.12269.x
复制
发表时间：
2007
影响因子：
4.8
通讯作者：
Emel'yanenko V
中科院分区：
文献类型：
--
作者：
Emel'yanenko V
奥尔特云的模型是利用覆盖4.5 Gyr的数值辛积分来计算行星、恒星和银河系的扰动而建立起来的。该模型与观测到的从奥尔特云注入到太阳系不同区域的彗星种群的广泛动力学特征是一致的。我们发现，大多数观测到的高离心率的海王星外天体、半人马座天体和短周期彗星在它们的动力学历史中都曾造访过奥尔特云（约1000天文单位）。根据观测假设，绝对星等h10 < 7，近日点距离q< 5 au和bbb104au的奥尔特云的近抛物通量大约是每年1颗彗星，我们的计算表明，目前奥尔特云的彗星数量为~ 5 × 1011颗h10 < 10.9的彗星。大约有一半的人有100万到104万美元。从奥尔特云到达行星区域的彗星的数量（1000天文单位）比在可观测的小于5天文单位的近日点距离高出一个数量级。同样，来自奥尔特云的每单位近日点距离的新彗星通量在近海王星区域比在可观测区域高几十倍。目前来自奥尔特云的高离心率海王星外天体（qbbb30 au和60 <a< 1000 au）的数量大约在1-3 × 1010的范围内，这取决于初始模型的细节。这些天体中有相当大一部分的b>200au和/ orqbb140au，它们大多起源于25 <q< 36au的初始轨道。同样地，从奥尔特云产生的半人马的数量，我们定义的半人马有5 <q< 28天文单位和< 1000天文单位，要少20-30倍。这些半人马座行星中，约有90%拥有60万au。访问过奥尔特云的天体代表了木星家族彗星数量的很大一部分，它们通过从太阳系外到近地空间的逐渐动态转移过程（包括半人马座阶段）实现了短周期轨道。除了众所周知的在小近日点距离上运行的扩散过程外，类似的机制也产生了哈雷彗星。
A model of the Oort cloud has been developed by accounting for planetary, stellar and Galactic perturbations using numerical symplectic integrations covering 4.5 Gyr. The model is consistent with the broad dynamical characteristics of the observed cometary populations injected from the Oort cloud into different regions of the Solar system. We show that the majority of observed high-eccentricity trans-Neptunian objects, Centaurs and short-period comets have visited the Oort cloud (a> 1000 au) during their dynamical history. Assuming from observations that the near-parabolic flux from the Oort cloud with absolute magnitudesH10< 7, perihelion distancesq< 5 au anda> 104au is approximately 1 comet per year, our calculations imply a present Oort cloud population of ∼5 × 1011comets withH10< 10.9. Roughly half this number havea> 104au. The number of comets reaching the planetary region from the Oort cloud (a> 1000 au) is more than an order of magnitude higher per unit perihelion distance immediately beyond Neptune than in the observable zoneq< 5 au. Similarly, the new-comet flux from the Oort cloud per unit perihelion distance is a few tens of times higher in the near-Neptune region than in the observable zone. The present number of high-eccentricity trans-Neptunian objects (q> 30 au and 60 <a< 1000 au) originating from the Oort cloud is in the approximate range 1–3 × 1010, depending on details of the initial model. A substantial fraction of these havea> 200 au and/orq> 40 au, and they are found mostly to originate from initial orbits with 25 <q< 36 au. Similarly, the number of Centaurs produced from the Oort cloud, where we define Centaurs to have 5 <q< 28 au anda< 1000 au, is smaller by a factor of 20–30. About 90 per cent of these Centaurs havea> 60 au. Objects that have visited the Oort cloud represent a substantial fraction of the Jupiter-family comet population, achieving short-period orbits by a process of gradual dynamical transfer, including a Centaur stage, from the outer Solar system to near-Earth space. A similar mechanism produces Halley-type comets, in addition to the well-known diffusion process operating at small perihelion distances.
登录
查看更多内容
奥尔特云彗星的大规模破坏
影响因子：
56.9
作者：
H. Levison;A. Morbidelli;L. Dones;R. Jedicke;P. Wiegert;W. Bottke
通讯作者：
W. Bottke
DOI：
--
发表时间：
1987
期刊：
影响因子：
--
作者：
J. Heisler;S. Tremaine;C. Alcock
通讯作者：
C. Alcock
所有彗星都去哪儿了？
影响因子：
56.9
作者：
M. Bailey
通讯作者：
M. Bailey
影响因子：
3.2
作者：
P. Wiegert;S. Tremaine
通讯作者：
P. Wiegert;S. Tremaine
影响因子：
3.2
作者：
H. Levison;M. Duncan
通讯作者：
H. Levison;M. Duncan