Isotopic studies of early planetesimals and planetary embryos

早期星子和行星胚胎的同位素研究

• 批准号: ST/F002130/1
• 负责人: Gretchen Benedix
• 金额: $ 0.51万
• 依托单位: Natural History Museum
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FF002130%2F1
• 关键词: Isotopic; studies; early; planetesimals; planetary

The research in this proposal tries to answer big questions about why we are here. Not just...why you and I are here. Not just...why humans are here. Not just...why animals evolved. Not even...why life started. But...why we have an Earth and Solar System at all. The best way to describe what this research will achieve is to list some good questions and then to explain what it is we are doing to try and figure out the answers. Question 1. What would it be like to roam around the Sun in a spaceship when the planets were being made? It would have been a lot more complicated than today because we are sure the planets formed from a swirling disk of gas and dust. We do not know how material moved around and mixed nor where many early objects came from. We can find out from precise measurements of small differences in the kinds of atoms present. These act as a kind of signature of bits of the disk and allow us to track motions rather like a detective uses fingerprints to trace a robber. Question 2. How were the planets created? We think that in this dusty disk the rock and debris somehow stuck together into tiny planets, which then dragged more rock onto them by gravity. Nobody knows exactly how this gets started. It is one of the biggest problems in planetary science. Gravity does not do much until an object is about the size of a small village. How to make things the size of a car or even a football pitch is harder to understand. We could test some theories if we knew how fast it happened. We will try and answer this by dating some of the meteorites that formed from early proto-planets. Question 3. Why do we have iron cores in terrestrial planets? We think the Earth's core formed from an ocean of molten rock created from the incredible heat resulting from accretion events like the Moon-forming Giant Impact. However, we do not understand how metal first formed and segregated from the first proto-planets. What provided the heat? It could have been radioactive energy or impacts. By finding out when melting and metal segregation occurred we can determine how it happened because radioactive isotopes and radiogenic heat production decay with time.

该提案中的研究试图回答有关我们为何来到这里的重大问题。不仅仅是……为什么你和我在这里。不仅仅是……为什么人类在这里。不仅仅是……动物为何进化。甚至不知道生命为何开始。但是……为什么我们有地球和太阳系。描述这项研究将取得的成果的最好方法是列出一些好的问题，然后解释我们正在做什么来尝试找出答案。问题 1：当行星正在形成时，乘坐宇宙飞船绕太阳漫游会是什么样子？那时的情况会比今天复杂得多，因为我们确信行星是由气体和尘埃的旋转盘形成的。我们不知道物质是如何移动和混合的，也不知道许多早期物体来自哪里。我们可以通过精确测量存在的原子种类的微小差异来找出答案。这些充当磁盘位的一种签名，使我们能够跟踪运动，就像侦探使用指纹追踪强盗一样。问题 2. 行星是如何创造的？我们认为，在这个尘土飞扬的圆盘中，岩石和碎片以某种方式粘在一起形成微小的行星，然后行星通过重力将更多的岩石拖到它们上面。没有人确切知道这是如何开始的。这是行星科学中最大的问题之一。当一个物体的大小与一个小村庄相当时，重力的作用并不大。如何制造出汽车甚至足球场大小的东西更难理解。如果我们知道它发生的速度有多快，我们就可以测试一些理论。我们将尝试通过测定一些早期原行星形成的陨石的年代来回答这个问题。问题3. 为什么类地行星上有铁核？我们认为地球的核心是由熔岩海洋形成的，熔岩海洋是由月球形成大撞击等吸积事件产生的令人难以置信的热量产生的。然而，我们不明白金属是如何首先形成并从第一颗原行星中分离出来的。是什么提供了热量？它可能是放射性能量或撞击。通过找出熔化和金属偏析何时发生，我们可以确定它是如何发生的，因为放射性同位素和放射性热产生随着时间的推移而衰减。