Galactic Astronomy at the University of Hertfordshire

银河系是我们的家园。伴随着它的是较小的卫星星系，其中最重要的是大小麦哲伦云。星系的演化与它们所包含的恒星的演化密切相关。星系中以气体形式存在的物质是恒星和行星系统形成的原材料。我们的团队研究了100亿年前在银河系诞生的第一批恒星--这一阶段现在只有在非常遥远的高红移星系中才能直接观察到。同样为了了解年轻的银河系是什么样子，我们研究了被称为白矮星的恒星，白矮星是早期极其微弱的恒星残骸。一些白矮星居住在双星中，预计双星将成为引力波的重要来源，其中一些最终将合并并以超新星的形式爆炸(恒星反馈到星际物质的化学和动力学的另一种途径)。为了解决恒星如何老化成为这些恒星残留物的问题，我们的团队研究了经过前一个极端红巨星演化阶段的恒星，包括银河系和麦哲伦云--这是恒星在强风阶段将物质返回星际气体的时刻。返回的气体通过在恒星内部进行的核聚变而得到化学浓缩，并将重新循环形成下一代恒星。银河系及其卫星是我们近距离观察这些过程的唯一机会。长波观测(在亚毫米波段和红外线下进行)使我们能够研究恒星和棕矮星的诞生。我们正在领导对我们银河系的新一代观测，旨在研究恒星的形成过程，从恒星在巨大的冷气云的重力作用下最初凝聚到由核聚变反应驱动的恒星的出现。新的调查将探测到数百个恒星正在形成的区域，包括大型星团和孤立的恒星。有了这个庞大的数据集，我们可以使用统计方法来确定恒星在整个银河系中形成的不同方式，以及这个过程所涉及的时间尺度。我们对附近恒星进行系统的径向速度搜索，以发现行星，然后对其中一些行星进行高分辨率成像和光谱分析，以辨别它们的大气属性。我们特别针对低质量恒星，既使用了多普勒摆动，也通过寻找周期性地遮盖其母恒星的行星。在授予期间，我们预计将在最近恒星的宜居带首次探测到地球质量的行星。此外，我们正在确定附近年轻的M星群体，我们将利用现有的和新的高分辨率设施瞄准这些恒星，以打开直接成像其他太阳系细节的可能性，这些细节的距离小到地球到太阳的距离。我们还发现、跟踪和模拟了最冷的失败恒星(褐矮星)的性质，它们的温度和性质与太阳系行星有很大的重叠，并洞察到围绕其他恒星轨道的行星以及它们本身。

The Milky Way is our home galaxy. It is accompanied by smaller satellite galaxies, the most important ones are the Large and Small Magellanic Clouds. The evolution of galaxies is closely linked to the evolution of the stars they contain. The matter in galaxies in the form of gas is the raw material for the formation of stars and planetary systems. Our group investigates the first stars born in the Milky Way over 10 billion years ago - a phase only directly observable now in very distant galaxies at high redshift. Also with a view to understanding what the young Milky Way was like, we study stars known as white dwarfs that are the extremely faint stellar remnants from these early days. Some white dwarfs reside in binaries, which are expected to be important sources of gravitational waves, and a few of them will eventually merge and explode as supernovae (another path way by which stars feed back into the chemistry and dynamics of interstellar matter). To solve problems in how stars age to become these stellar remnants, our group investigates stars passing through the preceding extreme red giant evolutionary phase, both in the Milky Way and the Magellanic Clouds -- this is the moment when stars return matter to the interstellar gas during a strong superwind phase. The returned gas is chemically enriched by nuclear fusion that has gone on inside the stars and will be re-cycled to form the next generation of stars. The Milky Way and its satellites are our only chance to have a close-up look at these processes. Long wavelength observations (made in the sub-mm and infrared) allow us to investigate the birth of stars and brown dwarfs. We are leading a new generation of surveys of our Milky Way Galaxy that are to designed to study the formation of stars from their initial condensation under gravity from vast clouds of cold gas to their emergence as stars powered by nuclear fusion reactions. The new surveys will detect hundreds of regions where stars are being formed, both in large clusters and in isolation. With this large dataset we can use a statistical approach to determine the different ways that stars can form in the Galaxy as a whole and the timescales involved in the process. We perform systematic radial velocity searches of nearby stars to discover planets and then follow some of these up with high resolution imaging and spectroscopy in order to discern their atmospheric properties. We especially target low mass stars both using Doppler Wobble and by looking for planets periodically eclipsing their parent star. During the period of the grant we expect to make the first detections of Earth-mass planets in the habitable zones of the closest stars. In addition we are identifying populations of nearby youthful M stars which we will target with existing and new high resolution facilities to open up potential to directly image the details of other Solar Systems at separations as small as that of the Earth to Sun distance. We also discover, follow-up and model the properties of the coolest failed stars (brown dwarfs) whose temperatures and properties offer substantial overlap with Solar System planets and insight into planets in orbit around other stars as well as on their own.