A Programme of Research in Astronomical Theory, Astronomical Observations and Planetary and Solar System Science

我们讨论了天体物理学的两个关键领域：恒星是如何由尘埃和气体云形成的，以及在我们的太阳系中可能对生命的出现起作用的化学过程是什么。磁场弥漫星际空间，在控制物质如何积聚到密度越来越高的核心方面发挥着至关重要的作用，因为引力在恒星-行星系统崩溃期间占据了主导地位。即使恒星的诞生地是寒冷和密集的，仍然有一些带电粒子，如电子、分子离子，更重要的是，带电的尘埃颗粒。我们将用计算机模拟研究带电尘埃颗粒的存在如何影响类似太阳的恒星的形成。事实证明，比太阳大得多的恒星的形成问题要大得多，因为它们稀有且遥远，会产生惊人的辐射，将物质吹走，而不是让它掉进去。当流入的物质接近恒星时，我们预计它将在围绕恒星运行的薄薄圆盘中完成其旅程。我们将使用红外干涉测量技术来寻找这些光盘。使用成像光谱仪，我们将寻找从圆盘的光谱线相对于星光的微小空间位移，以获得比哈勃太空望远镜好10到100倍的空间信息。同时，这种物质通过圆盘螺旋进入恒星，其中一些物质被磁场沿着旋转轴高速抛出。我们将使用英国高度敏感的新无线电天线网络e-Merlin来绘制这些喷气式飞机的辐射地图，并研究这些辐射是如何进入周围不断涌入的分子材料中的。分子发射的详细图谱将使用智利的新ALMA望远镜进行，其中66个碟子在微波频率下协调工作。无线电和微波相结合的研究将使我们能够找出磁力何时让位于强大的辐射压力。随着大质量恒星最终开始清除它们出生的物质，它们强大的辐射场驱动的风的综合效应产生了戏剧性的影响。正如NASA的钱德拉卫星所观察到的那样，当风猛烈撞击分子材料并相互作用时，它们在X射线区域发出强烈的辐射。最大质量的恒星寿命如此之短，只有几百万年，以至于它们可以作为超新星爆炸，同时仍然被分子云的残余物包围。计算机模拟将被用来解决这个问题，以研究这些过程如何终止巨型分子云中的恒星形成过程。在遥远的原始星系中，大质量恒星的形成主导了我们所看到的大部分。化学模型和观测将帮助我们了解第一代恒星是如何进化的。由于外层受到辐射压力的驱赶，即将寿终正寝的大质量恒星也失去了大部分质量。这些过程将使用上述高分辨率红外技术进行观测研究。当两颗质量较大的演化恒星处于接近的双星系统时，它们的风也会相互碰撞，产生X射线辐射。数值模拟将被用来研究这些过程。土星的卫星之一土卫六引起了人们的极大兴趣，因为它与早期的地球有相似之处。卡西尼惠更斯任务发现，大气中的苯比预期的要多，而表面(湖泊而不是深海)的乙烷更少。我们将进行一系列实验室研究，以确定大气中这些物种的形成和移除速度，并通过纳入化学模型来衡量我们的结果的影响。气象卫星保留了对早期太阳系的记忆，它们的化学组成可以帮助我们了解生命的起源。铁陨石上的实验将研究电子转移对生物前分子的作用。

We address two key areas of astrophysics: how do stars form from clouds of dust and gas and what chemical processes are at work in our solar system that may play a role in the emergence of life. Magnetic fields pervade interstellar space and play a crucial role in controlling how material can accumulate into ever denser cores as gravity takes hold during the collapse to a star-planet system. Even though stellar birth sites are cold and dense there are still some charged particles such as electrons, molecular ions and, importantly, charged grains of dust. We will investigate with computer simulations how the presence of charged dust grains affects the formation of stars similar to our Sun.The formation of stars much more massive than our Sun has proved to be much more problematic as they are rare and distant and produce prodigious amounts of radiation that blow material away rather than let it fall in. As the infalling material gets close in to the star we expect it to complete its journey in a thin disc orbiting the star. We will search for these discs using the techniques of infrared interferometry. With imaging spectrographs we will look for tiny spatial shifts from spectral lines from the disc relative to the starlight to gain spatial information at levels 10 to 100 times better than the Hubble Space Telescope.At the same time that material is spiralling onto a star via a disc, some of it is being ejected at high speeds along the rotation axis by magnetic fields. We will use the highly sensitive new network of radio dishes in the UK, e-MERLIN, to map the emission from these jets and study how these plough into the surrounding infalling molecular material. The detailed mapping of the molecular emission will be carried out with the new ALMA telescope in Chile where 66 dishes work in unison at microwave frequencies. Combined radio and microwave studies will allow us to find out when the magnetic forces give way to the strong pressure of radiation.As massive stars finally begin to clear away the material from which they were born, the combined effect of the winds driven by their strong radiation fields has a dramatic effect. As the winds slam into the molecular material, and each other, they emit strongly in the X-ray region as observed with NASA's Chandra satellite. The most massive stars have such short lives of a few million years, that they can blow up as supernovae whilst still surrounded by the remnants of the molecular clouds. Computer simulations will be used to tackle this problem to investigate how these processes can terminate the star formation episodes in giant molecular clouds. In distant, primeval galaxies, massive star formation dominates much of what we see. Chemical models and observations will be used to help us understand how the first generations of stars evolve. Massive stars that are nearing the end of their lives also lose much of their mass due to the radiation pressure driving off their outer layers. These processes will be investigated observationally using the high resolution IR techniques described above. When two massive evolved stars are in a close binary system their winds also smash into each other giving rise to X-ray emission. Numerical simulations will be used to investigate these processes. Titan, one of Saturn's moons, is of great interest as there are analogies to the early Earth. The Cassini Huygens mission found that there is more benzene than expected in the atmosphere and less ethane on the surface (lakes rather than deep oceans). We will carry out a range of laboratory studies to determine the atmospheric rates of formation and removal of these species and gauge the impact of our results through inclusion in chemical models.Meteorites preserve a memory of the early solar system and their chemical make-up can help us understand the origins of life. Experiments on iron meteorites will investigate the role of electron transfer on pre-biotic molecules.