Triggered planet formation in young stellar clusters

触发年轻恒星团中的行星形成

• 批准号: 28423377
• 负责人: Professor Dr. Pavel Kroupa
• 金额: --
• 依托单位: Helmholtz-Institut für Strahlen- und Kernphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/28423377?language=en
• 关键词: Triggered; planet; formation; young; stellar

Understanding the origin of the planets is one of the oldest astrophysical research fields, and there are still unanswered principal questions. One of them is how Uranus and Neptune formed within the limited available time during the existence of the protoplanetary disk, from the reservoir of material out of which the planets formed. According to observational and theoretical data the lifetime of such a disk has been estimated to be less than about ten million years. On the other hand, the widely accepted model of planet formation - collisions of planetesimals followed by gravitational accretion of surrounding material - would take more than 100 million years especially for the outermost giant planet Neptune and even longer for the large trans-Neptunian objects (TNOs) like Sedna or the recently discovered 2003 UB313 (often referred to as Xena in the media). Another question concerns the orbits of the discovered extrasolar planets (exoplanets), which have high eccentricities and inclinations in contrast to the nearly circular orbits in the Solar System. The project outlined here addresses both these fundamental questions. The central idea postulates a close encounter between the very young Sun and a (most likely) low-mass star within the native stellar cluster of our Solar System. Such an encounter could cause local gravitational instabilities that fragment and collapse, forming protoplanetary cores of sufficient mass for a quick following accretion process. The aim is to investigate this scenario by hydrodynamical computations of the overall physics within the disk down to the process of gravitational collapse and planet core formation, and subsequent accretion.

了解行星的起源是最古老的天体物理学研究领域之一，目前仍有一些主要问题没有得到解答。其中之一是天王星和海王星是如何在原行星盘存在的有限时间内，从形成行星的物质储存库中形成的。根据观测和理论数据，这样一个圆盘的寿命估计不到1000万年。另一方面，被广泛接受的行星形成模型——星子的碰撞，随后是周围物质的引力吸聚——将需要超过1亿年的时间，尤其是对最外层的巨行星海王星来说，对于像塞德娜或最近发现的2003 UB313（在媒体中通常被称为Xena）这样的大型海王星外天体（TNOs）来说，甚至更长。另一个问题与已发现的太阳系外行星（系外行星）的轨道有关，它们与太阳系中接近圆形的轨道相比，具有很高的离心率和倾斜度。这里概述的项目解决了这两个基本问题。其中心思想假定非常年轻的太阳与我们太阳系内的一颗（最有可能的）低质量恒星之间的近距离接触。这样的相遇可能会导致局部引力不稳定，导致碎片和坍缩，形成足够质量的原行星核心，以供随后的快速吸积过程使用。目的是通过流体力学计算来研究这种情况，计算盘内的整体物理过程，直至引力坍缩和行星核心形成以及随后的吸积过程。