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Isotopic studies of solar system formation and early development

太阳系形成和早期发展的同位素研究

基本信息

批准号：
PP/D001250/1
负责人：
Alex Halliday
金额：
$ 97.31万
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=PP%2FD001250%2F1
关键词：
Isotopic studies solar system formation

项目摘要

The research in this proposal tries to answer a string of 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 a Sun and 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. Why do we have a Sun? We think the Sun formed from a huge mass of gas and dust like the clouds you see in pictures of the Orion Nebula. Stars like our Sun are not unusual, but it is hard to see them forming. It must happen by gravity pulling all the gas and dust into one spot. But what makes that happen? Does it just - happen? Some scientists think it takes a shock wave from another star to force the gas and dust to move together so that gravity starts to become really powerful - powerful enough to get everything to collapse and form a new star. The shock wave that started it all may have come from a supernova explosion. We expect to find out by analysing meteorites to find tell-tale signs of atoms that can only have been made in a supernova. Question 2. 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 much about how the disk rotated or whether stuff was thrown on to it from the Sun. 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 3. 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 tennis court 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 baby-planets. We can also tell that rocky planets like Earth took longer - roughly 50 million years. Jupiter must have formed fast because it is made of gas that would have been lost otherwise. Now we have evidence that Mars, a small planet, actually formed very fast, at the exact same time as Jupiter should have been forming a bit further away. Maybe Jupiter scoffed up all the dust and debris and did not leave much for Mars to get any bigger. The first thing to do is to check out this evidence and see if it is right. Question 4. How did the Moon form and why is it so different from Earth? We think the Moon formed from the debris left from a collision between Earth and another planet. The debris was so hot that it was vaporised and some was lost to space. Water is not the only thing that was lost. We have evidence that some of the iron metal was boiling! We need to check out this theory with more measurements and see what else evaporated when planets were made. Question 5. Why do we have an iron core in our planet? We think the core formed from an ocean of molten rock created from the incredible heat resulting from the Moon-forming Giant Impact. Somehow the Earth must have cooled down from this amazing fireball to the pleasant place it is today. We think we can now date when different bits of the core formed. In fact, this will tell us how fast the Earth was cooling down after the Moon formed. From this we should be able to figure out when the Earth might have become okay for there to be oceans of water suitable for life to develop.

这项提案中的研究试图回答一系列关于我们为什么会在这里的大问题。不仅仅是...为什么你和我会在这里。不仅仅是...为什么人类会在这里。不仅仅是……为什么动物会进化。甚至不知道...为什么生命开始了。但是……为什么我们有太阳、地球和太阳系呢？描述这项研究将实现什么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试图找出答案。问题1.为什么我们会有太阳？我们认为太阳是由巨大的气体和尘埃形成的，就像你在猎户座星云图片中看到的那样。像我们的太阳这样的恒星并不罕见，但很难看到它们的形成。它必须通过引力把所有的气体和尘埃拉到一个点上。但是什么让这一切发生的呢？它就这么-发生了吗？一些科学家认为，需要来自另一颗恒星的冲击波才能迫使气体和尘埃一起运动，从而引力开始变得非常强大--强大到足以让一切坍塌并形成一颗新的恒星。引发这一切的冲击波可能来自一次超新星爆炸。我们希望通过分析陨石，找到只能在超新星中形成的原子的迹象，从而找出答案。问题2：当行星正在形成的时候，乘坐宇宙飞船绕太阳飞行会是什么感觉？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组成的漩涡盘形成的。我们不太清楚这个圆盘是如何旋转的，也不知道是否有东西从太阳扔到它上面。我们可以从对存在的原子种类的微小差异的精确测量中找到答案。这就像是磁盘上的比特的一种签名，让我们能够跟踪移动，就像侦探用指纹追踪强盗一样。问题3：行星是如何形成的？我们认为，在这个尘土飞扬的圆盘中，岩石和碎片不知何故粘在一起，形成了小行星，这些行星随后在重力的作用下将更多的岩石拖到了行星上。没有人确切地知道这是如何开始的。这是行星科学中最大的问题之一。直到一个物体大到一个小村庄的大小，重力才起到很大的作用。如何把东西弄成网球场甚至足球场的大小就更难理解了。如果我们知道它发生得有多快，我们就可以检验一些理论。我们将尝试通过测定一些由早期幼行星形成的陨石的年龄来回答这个问题。我们还可以断定，像地球这样的岩石行星需要更长的时间--大约5000万年。木星一定是快速形成的，因为它是由气体组成的，否则就会失去。现在我们有证据表明，火星这颗小行星实际上形成得非常快，与木星形成的时间正好相同，应该在更远的地方形成。也许木星吃掉了所有的尘埃和碎片，没有留下太多让火星变大的东西。首先要做的是检查这些证据，看看它是否正确。问题4：月球是如何形成的？为什么它与地球如此不同？我们认为月球是由地球与另一颗行星碰撞后留下的碎片形成的。碎片是如此之热，以至于它被蒸发了，一些碎片丢失到了太空中。水并不是唯一丢失的东西。我们有证据表明一些铁金属正在沸腾！我们需要用更多的测量来检验这一理论，看看当行星形成时还蒸发了什么。问题5.为什么我们的星球上有一个铁核？我们认为，形成月球的核心是由形成月球的巨型撞击产生的令人难以置信的热量产生的熔岩海洋形成的。不知何故，地球一定是从这个令人惊叹的火球冷却到了今天这个令人愉快的地方。我们认为我们现在可以确定不同的核心部分形成的时间。事实上，这将告诉我们月球形成后地球冷却的速度有多快。从这一点上，我们应该能够计算出，地球何时可能变得可以形成适合生命生长的水海洋。