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The formation, structure, and evolution of molecular clouds, stars, and planets

分子云、恒星和行星的形成、结构和演化

基本信息

批准号：
ST/M00127X/1
负责人：
Timothy Harries
金额：
$ 97.67万
依托单位：
UNIVERSITY OF EXETER
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FM00127X%2F1
关键词：
formation structure evolution molecular clouds

项目摘要

Our research is focussed on improving our understanding of how stars and planets form, and the physical processes that occur both deep in the interior and in the outer layers of stars and planets. We intend to achieve this goal using a combination of computer modelling and observations.Stars form from molecular clouds, and we will examine the structure of this turbulent gas, since this has a strong influence on how they collapse under gravity. We will look at a nearby ring of star forming regions, called the Gould Belt, using an extensive survey taken at sub-millimetre wavelengths, testing our models of how stars form and looking for evidence of the earliest stages of protostars. We will also use computer models to investigate how the Gould Belt formed, since it may be that supernova explosions are the key to creating its ring-like structure.The collapse of a molecular cloud results in a cluster of stars with a variety of masses. Most stars are less massive than the Sun, and some objects have such low masses that they do not fuse hydrogen in their cores. These objects are known as brown dwarfs and they are hot when they are formed but cool over time. By examining the statistical properties of clusters of stars we will be able to measure the initial distribution of stellar masses, and this will enable us to test how brown dwarfs cool. Although most stars are less massive than the Sun, some can be over twenty times as massive and are extremely bright. The formation of these giant stars is fundamentally a competition between gravity and the outward pressure exerted by the starlight. We will use computer simulations to investigate how such stars form, and compare our simulations to observations from ground- and space-based telescopes.Newly forming stars are surrounded by dense discs of dust and gas. We will use interferometry, an observational method that combines light collected by several telescopes together, to measure the structure of these discs. Sophisticated computer models will be used to investigate the protostar-disc interaction. It is known that planets form in such discs, and we will use sophisticated computer models to simulate how a proto-planet coalesces out of the dust and gas. Once the star and planet system has fully formed, the only dust that is left is generated by asteroids colliding together, a so-called debris disc. We will use adaptive optics (a high-resolution observational techniques that corrects for the distorting effect of the Earth's atmosphere) to identify newly formed planets around young stars and examine the gravitational effect of these exoplanets on the debris discs.We will investigate the atmospheres of so-called Hot Jupiters - exoplanets that are strongly irradiated by their host stars. This research uses the Met Office's computer model for the Earth's climate, which has been specially adapted to deal with the different physical process that occur in exoplanet atmospheres. We will also use computer models to investigate the interior structure of Jupiter and Saturn, planets whose shape is distorted by their rapid rotation. We will compare our results to observations made by the Juno and Cassini space probes.The solar wind is a continuous stream of plasma flowing away from the Sun. The Sun and large disturbances in the solar wind affect our climate and causes, for instance, communication drop-outs, power outages and radiation exposure on transatlantic flights. We will investigate the physics of the Sun using a combination of theory and observations. We will examine properties of the solar magnetic field, at the Sun and near Earth in the solar wind, that indicate ways in which it can twist and kink. Build up of twisting can lead to enhanced solar activity, which has implications for the prediction of space weather. We will also use computer models to look at how turbulent motions in the Sun are produced as the ionised gas interacts with the Sun's magnetic field.

我们的研究重点是提高我们对恒星和行星如何形成，以及恒星和行星内部和外层深处发生的物理过程的理解。我们打算结合计算机建模和观测来实现这一目标。恒星由分子云形成，我们将检查这种湍流气体的结构，因为这对它们在重力作用下如何塌缩有很大影响。我们将利用在亚毫米波长下进行的广泛调查来观察附近的一个称为古尔德带的恒星形成区域环，测试我们的恒星形成模型并寻找原恒星最早阶段的证据。我们还将使用计算机模型来研究古尔德带是如何形成的，因为超新星爆炸可能是形成其环状结构的关键。分子云的塌陷导致了具有不同质量的恒星团。大多数恒星的质量都小于太阳，有些天体的质量如此之低，以至于它们的核心不会融合氢。这些天体被称为褐矮星，它们形成时很热，但随着时间的推移会变冷。通过检查星团的统计特性，我们将能够测量恒星质量的初始分布，这将使我们能够测试褐矮星如何冷却。尽管大多数恒星的质量都小于太阳，但有些恒星的质量可能是太阳的二十倍以上，而且非常明亮。这些巨星的形成从根本上来说是引力与星光向外施加的压力之间的竞争。我们将使用计算机模拟来研究这些恒星是如何形成的，并将我们的模拟与地面和太空望远镜的观测结果进行比较。新形成的恒星被密集的尘埃和气体盘包围。我们将使用干涉测量法（一种将多台望远镜收集的光结合在一起的观测方法）来测量这些圆盘的结构。复杂的计算机模型将用于研究原恒星盘相互作用。众所周知，行星是在这样的圆盘中形成的，我们将使用复杂的计算机模型来模拟原行星如何从尘埃和气体中凝聚出来。一旦恒星和行星系统完全形成，剩下的唯一尘埃就是小行星碰撞在一起产生的，即所谓的碎片盘。我们将使用自适应光学（一种高分辨率观测技术，纠正地球大气层的扭曲效应）来识别年轻恒星周围新形成的行星，并检查这些系外行星对碎片盘的引力效应。我们将研究所谓的热木星的大气层，这些系外行星受到其主恒星的强烈辐射。这项研究使用了英国气象局的地球气候计算机模型，该模型经过专门调整，可以处理系外行星大气中发生的不同物理过程。我们还将使用计算机模型来研究木星和土星的内部结构，这些行星的形状因快速自转而扭曲。我们将把我们的结果与朱诺号和卡西尼号太空探测器的观测结果进行比较。太阳风是远离太阳的连续等离子体流。太阳和太阳风的巨大扰动会影响我们的气候，并导致例如跨大西洋航班的通信中断、停电和辐射暴露。我们将结合理论和观测来研究太阳的物理学。我们将研究太阳风中太阳磁场的特性，这些特性表明太阳磁场可以扭曲和扭结的方式。扭曲的积累会导致太阳活动增强，这对太空天气的预测具有影响。我们还将使用计算机模型来研究当电离气体与太阳磁场相互作用时，太阳中的湍流运动是如何产生的。