Early evolution of the birth cluster of the solar system
Early evolution of the birth cluster of the solar system
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DOI：
10.1051/0004-6361/201218792
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发表时间：
2012-10
影响因子：
6.5
通讯作者：
S. Pfalzner
中科院分区：
文献类型：
--
作者：
S. Pfalzner
上下文太阳系很可能诞生于一个至少包含1000颗恒星的星星星团。这种星团环境极有可能影响到太阳系的各种性质，例如其化学组成、大小和某些组成天体的轨道参数。目标。在银河系中，超过2000颗恒星的星团只形成两种类型-星爆星团和泄漏星团-每一种都遵循质量半径平面上独特的时间发展。这里的目的是确定遇到概率的范围内有关的太阳系形成星爆或泄漏集群环境作为集群年龄的函数。方法.用N体方法研究了盘状太阳型年轻恒星的星团动力学和星团成员间引力相互作用效应。结果使用现有的知识，在一个给定的集群年龄的集群密度表明，在星爆集群的中心密度超过第一个500万年是如此之高（最初> 10 - 5百万pc 3），几乎没有任何光盘与太阳系建设潜力将生存这一阶段。这使得星爆星团不太可能是我们太阳系形成的环境。相反，太阳系极有可能形成于一个漏星系团（通常被归类为OB星协）。它表明，确定我们的太阳系中存在的特征属性的遭遇最有可能发生在其形成历史的早期（<200万年），并在500万年后，一个太阳型星星经历这样的遭遇在一个泄漏的集群的可能性是可以忽略不计的，即使它仍然是绑定残余的一部分。这就解释了为什么太阳系能够发展并在后来的发展中保持其高圆形。
Context. The solar system was most likely born in a star cluster containing at least 1000 stars. It is highly probable that this cluster environment influenced various properties of the solar system like its chemical composition, size and the orbital parameters of some of its constituting bodies. Aims. In the Milky Way, clusters with more than 2000 stars only form in two types - starburst clusters and leaky clusters - each following a unique temporal development in the mass-radius plane. The aim is here to determine the encounter probability in the range relevant to solar system formation for starburst or leaky cluster environments as a function of cluster age. Methods. N-body methods are used to investigate the cluster dynamics and the e ect of gravitational interactions between cluster members on young solar-type stars surrounded by discs. Results. Using the now available knowledge of the cluster density at a given cluster age it is demonstrated that in starburst clusters the central densities over the first 5Myr are so high (initially> 10 5 M pc 3 ) that hardly any discs with solar system building potential would survive this phase. This makes a starburst clusters an unlikely environment for the formation of our solar system. Instead it is highly probable that the solar system formed in a leaky cluster (often classified as OB association). It is demonstrated that an encounter determining the characteristic properties existing in our solar systems most likely happened very early on (< 2Myr) in its formation history and that after 5Myr the likelihood of a solar-type star experiencing such an encounter in a leaky cluster is negligible even if it was still part of the bound remnant. This explains why the solar system could develop and maintain its high circularity later in its development.