Sounding the Stars: OCTAVE, the Birmingham Seismology Programme

恒星是宇宙可见的组成部分，离我们最近的恒星太阳对地球上的生命至关重要。我们的研究旨在“观察”太阳和恒星的内部，以帮助我们了解它们是如何工作和进化的。虽然你没有特殊的设备是看不到它的，但太阳在颤抖，很多星星也在颤抖。恒星可见表面下的气泡运动不断地补充能量，恒星的反应是振动，就像(非常)大的乐器一样。天文学家对恒星的“笔记”很感兴趣。它们是由深入内部的声波产生的，它们的频率(音调)取决于它们在传播过程中遇到的条件，如恒星物质的密度和温度。通过对它们的研究，天文学家基本上得到了一颗恒星的超声波扫描--我们可以更好地了解从最初是什么产生振动，一直到恒星核心的核反应堆的一切。通过研究太阳，我们对一颗恒星进行了细致的检查，同时获得了一系列恒星的信息，这使得我们能够测试我们的恒星模型，这些恒星具有不同的质量、组成和年龄。然后我们可以研究像太阳这样的恒星是如何进化的--我们可以看到太阳的未来，将这些想法转化为科学现实是非常困难的。震动非常小--表面以每秒几米的速度来回移动(在太阳能情况下)，周期约为5分钟。仅仅是探测微小的运动就需要专门设计的仪器(称为光谱仪，因为它们可以检测恒星的光谱)。与此同时，这颗恒星的亮度变化约为万分之一，太阳只能从地球上探测到，但太微妙了，无法通过地球大气层在其他恒星上测量到。对恒星的一些有趣的影响可以持续几年。例如，我们知道恒星有磁场活动的周期，但我们还不完全了解--太阳的周期大约每11年有一次“黑点”周期。由于这个和其他的原因，你真的想要连续多年地观察恒星的振动。一种方法是在世界各地放置许多机器人光谱仪，这样当一颗恒星落在一台仪器上时，它已经升到了另一台仪器上。通过运营伯明翰太阳振荡网络(BISON)，我们已经为太阳做了大约30年的这项工作，现在的目标是利用这些专业知识开发一个研究恒星的网络。丹麦的同事们正在为恒星振荡网络小组(SONG)设计原型仪器。我们的目标是为仪器设计和控制做出贡献，以帮助SONG开发，以及继续我们的太阳观测。研究恒星振荡的另一种方法是从太空观察它们的微小亮度波动，目前的一些卫星可以做到这一点。我们开发的研究太阳的技术可以转移到其他恒星和卫星数据上。近年来，我们一直在与国际同行合作，为NASA卫星开普勒将产生的数据做准备(从2009年年中开始)，我们的目标是在未来几年对数百颗恒星进行研究。我们还将使用SMEI卫星的数据来研究O星和B星的非常不同的脉动，这两颗星比太阳热得多。在这里，脉动是如此剧烈，以至于它们可能在恒星从外层失去质量的过程中发挥了作用--我们的工作将有助于研究这种质量损失。因此，我们的新建议是将我们的观测和分析经验从我们的太阳工作扩展到其他恒星，并继续运营野牛网络，收集高质量的太阳数据。我们将使用恒星和太阳数据来提供有关恒星深部的新信息(特别是研究恒星演化)，并改善我们对恒星活动周期和产生振动的恒星外层对流层的理解。

Stars are the visible building-blocks of the Universe and the nearest star to us, the Sun, is vital to life on Earth. Our research aims to 'look' deep inside the Sun and stars to help us understand how they work and evolve. Although you can't see it without special equipment, the Sun is shaking, and many stars are too. Bubbling motion just under the visible surface of the star constantly feeds in energy, and the star responds by vibrating like a (very) large musical instrument. The 'notes' of the stars are very interesting to astronomers. They are produced by sound waves which have travelled deep inside and their frequencies (the 'pitches' of the notes) depend on the conditions they meet on the way, such as the density and temperature of stellar material. By studying them astronomers essentially get an 'ultrasound scan' of a star - we can understand better everything from what makes the vibrations in the first place, all the way to the nuclear reactor at the star's core. By studying the Sun we examine one star in exquisite detail, whilst gaining information on a range of stars allows us to test our models of stars with different masses, compositions and ages. We can then study how stars like the Sun evolve - we can see the future of the Sun Turning these ideas into scientific reality is very difficult. The shaking is very small - the surface moves to and fro at a couple of metres per second (in the solar case) and cycles in about 5 minutes. Just detecting the small movements takes specially designed instruments (called spectrometers, because they examine a star's spectrum). At the same time the star's brightness changes by about 1 part in 10,000, just detectable from Earth for the Sun, but too subtle to be measured in other stars through the Earth's atmosphere. Some interesting effects on stars can last for several years. For example, we know that stars have cycles of magnetic activity which we don't fully understand yet - the Sun's has periods of 'spottiness' every 11 years or so. For this and other reasons, you would really like to observe the stars' vibrations continuously for many years. One way is to put a number of robotic spectrometers in different places around the world, so that when a star sets on one instrument it has already risen on another. We have been doing this for the Sun for about 30 years, by operating the Birmingham Solar Oscillations Network (BiSON), and now aim to use this expertise in the development of a network for studying stars. Colleagues in Denmark are designing the prototype instrument for SONG (the Stellar Oscillations Network Group). We aim to contribute to instrument design and control to help SONG develop, as well as continuing our solar observations. Another way to study the oscillations of stars is to observe their small brightness fluctuations from space, and a number of current satellites can do this. Techniques we have developed for studying the Sun are transferrable to other stars and the satellite data. We have been working in recent years with international colleagues to prepare for data that the NASA satellite, Kepler, will produce (from the middle of 2009) and we aim to work on hundreds of stars in the coming years. We will also use data from the SMEI satellite to study the rather different pulsations of O and B stars, which are much hotter than the Sun. Here the pulsations are so dramatic that they may play a part in the stars losing mass from their outer layers - our work will help to examine this mass loss. So our new proposal is to extend our observational and analytical experience from our solar work to other stars and to continue to operate the BiSON network, collecting high quality solar data. We will use stellar and solar data to provide new information on the deep interiors of stars (especially to study stellar evolution) and to improve our understanding of stellar activity cycles and of the outer convective layers of stars where the vibrations are generated.