The transient sky: an integrated programme of study 2011 - 2016

在肉眼看来，夜空似乎是恒定的，除了月亮和更明亮的行星的运动，以及偶尔经过的彗星或流星。然而，详细的观察显示，这与事实相去甚远。许多恒星的亮度不同，要么是由于内在的可变性，要么是因为一颗绕其轨道运行的行星(称为凌日系外行星)从它前面经过，挡住了一部分星光。用大型望远镜拍摄的照片显示，微弱的小太阳系天体围绕太阳运行，因此改变了它们在夜空中的位置。这样的曝光也揭示了遥远星系中恒星以超新星的形式爆炸。即使是太阳--天空中最亮的物体--也在不断变化。其表面的巨大爆炸被称为耀斑，发生的时间跨度从几分钟到几个小时不等。最近，用高速相机对太阳的观测表明，太阳大气的变化可以发生在远不到一秒的时间尺度上。所有这些现象都导致了所谓的瞬变天空，即外观随时间变化的天空。我们计划一个观测和理论天体物理学的协调方案来研究这种现象。这将利用专门为调查瞬息万变的天空而开发的仪器和设施，时间从不到一秒到几个月不等。我们的滚动赠款方案将涵盖的主要主题包括：利用ROSA成像仪以高时间分辨率研究太阳大气中的活动和变异性；利用SuperWASP和RISE设施发现凌日系外行星并确定其特征；利用泛星巡天获得的数据探测太阳系天体和超新星。我们的滚动资助计划亦会广泛利用其他主要的STFC设施，对太阳、系外行星、太阳系天体和超新星，以及以超新星形式爆发的恒星进行跟进和补充观测。这些设施包括Hinode太阳飞行任务和哈勃空间望远镜等卫星，以及大型地面望远镜，包括智利欧洲南方天文台的8米直径甚大望远镜和加那利群岛拉帕尔马艾萨克牛顿天文台的4米直径威廉·赫歇尔望远镜。

To the naked eye, the night sky appears constant, apart from the motion of the Moon and brighter planets, and the passing of the occasional comet or meteor. However, detailed observations reveal that this is far from the truth. Many stars vary in brightness, either due to intrinsic variability or because an orbiting planet (called a transiting exoplanet) passes in front of it, blocking out a portion of the starlight. Faint, small Solar System bodies, orbiting the Sun and hence changing their position in the night sky, are revealed on exposures taken with large telescopes. Such exposures also reveal stars exploding as supernova in distant galaxies. Even the Sun - the brightest object in the sky - is continually changing. Giant explosions on its surface, known as flares, take place over timescales of minutes to hours. Recently, observations of the Sun with high-speed cameras reveal that changes in the solar atmosphere can occur over timescales of much less than a second. All these phenomena lead to what is termed the transient sky, i.e. a sky whose appearance varies with time. We plan a coordinated programme of observational and theoretical astrophysics to study such phenomena. This will make use of instruments and facilities developed specifically for the investigation of the transient sky, on timescales ranging from less than a second to months. Major themes which will be covered by our Rolling Grant programmes include: the study of activity and variability in the solar atmosphere at high time resolution with the ROSA imager; the discovery and characterisation of transiting exoplanets by the SuperWASP and RISE facilities; the detection of Solar System bodies and supernovae using data obtained from the Pan-STARRS sky survey. Our Rolling Grant programmes will also make extensive use of other major STFC facilities for followup and complementary observations of the Sun, exoplanets, Solar System bodies and supernovae, as well as the stars which explode as supernovae. These facilities include satellites, such as the Hinode solar mission and the Hubble Space Telescope, and large ground-based telescopes including the 8-metre diameter Very Large Telescope at the European Southern Observatory in Chile, and the 4-metre diameter William Herschel Telescope at the Isaac Newton Observatory on La Palma in the Canary Islands.