Discovery, characterisation and understanding of extrasolar telluric and ice planets with transits

直到最近，我们只有一个行星系统，太阳系，用来测试我们关于行星如何形成和演化的想法。自从1995年发现了第一颗围绕另一颗正常恒星发现的行星以来，已经发现了200多颗太阳系外的行星，我们正在开始将地球和太阳系置于它们的宇宙背景中。迄今为止的探索主要集中在气态巨行星上，但新的仪器和空间飞行任务现在使探测和研究主要由冰或水和岩石组成的较小行星成为可能，如天王星或类似海王星的行星，但也有假想的非常大质量的岩石行星/“超级地球”/或具有深表层水的行星/“海洋行星”。早期的结果表明，这些岩石/冰行星在类太阳恒星周围相对常见。探测到它们是朝着发现能够支持生命的太阳系外行星迈出的重要一步，也让我们了解了类地行星的形成方式。我的提议旨在为这些行星研究的所有阶段做出贡献：发现、表征和理解。第一步是发现行星，为此我使用了两种互补的方法。径向速度法测量恒星在行星引力下的反射运动，我将与欧洲天文学家合作，用先进的光谱仪HARPS和SOFIE(智利的ESO和法国的OHP)来测量它。我的主要专长是第二种方法，凌日方法，它测量行星从它前面经过时恒星的暗淡程度。我已经参与了对十几颗气态巨行星凌日的探测，以及目前已知的唯一一颗凌日的海王星质量的行星(GJ436b)。我将在CoRoT太空望远镜的数据中搜索新的凌日岩石/冰行星，以及使用小型地面望远镜搜索已知低质量行星的凌日。下一步是测量它们的特性。当一颗行星经过它的母星，或者在轨道的另一边经过它的后面时，可能会有独特的强大的观测，这些观测揭示了关键的属性，如质量、半径、体积组成和大气温度。哈勃太空望远镜(HST)和斯皮策红外太空望远镜设备(SIRTF)在过去几年中开辟了这一领域。我最近领导了一个团队，使用hst首次在这颗巨大行星的伴星HD 189733的大气中探测到了高海拔的雾霾，并计划很快在GJ进行类似的观测。在接下来的几年里，我将继续使用太空设施来描述新发现的低质量行星。我还打算使用较小的地面望远镜来监测已知行星的凌日。这些时间紧迫的观测在正常的地点很难安排，而南极洲由于几个月的持续黑暗，已经成为一个有希望的替代选择。我参加了一个项目，在南极高原中部的穹顶C安装一个小型望远镜进行凌日观测，埃克塞特天体物理学小组已经参与了那里的一些天文项目。该计划的最终目的是通过将探测到的不同类型行星的数量和性质与理论模型预测的结果进行比较，提高我们对岩石/冰行星的形成、演化和结构的理解。这不仅需要计算我们看到的，也需要计算我们错过的。我调查了常用行星探测方法中的偏差，以及我们测量的属性的不确定程度。我还与专门为恒星结构建模的同事一起，开始为岩石/冰行星开发结构模型，我计划通过与行星形成专家合作来扩展这一模型。然后，我将把这一点应用于前面提到的观测项目的结果，以建立对其结果的统计影响的端到端视图。

Until recently, we had only one planetary system, the Solar system, against which to test our ideas of how planets form and evolve. Since the discovery, in 1995, of the first planet found around another normal star, over 200 other extra-solar planets have been discovered, and we are starting to place the Earth and the Solar system in their cosmic context. Exploration to date focussed on gaseous giant planets, but new instruments and space missions now make it possible to detect and study smaller planets, mainly composed of ice or water and rocks, such as Uranus or Neptune-like planets, but also hypothetical very massive rocky planets / 'super Earths' / or planets with a deep surface layer of water / 'ocean planets'. Early results suggest these rock/ice planets are relatively common around Sun-like stars. Detecting them is a major step towards discovering extrasolar planets capable of supporting life, but also teaches us about the way Earth-like planets form. My proposal aims to contribute to all stages of the study of these planets: discovery, characterisation, and understanding. The first step is to discover the planets, for which I use two complementary methods. The radial velocity method measures the reflex motion of the star due to the pull of the planet, and I will pursue it with the advanced spectrographs HARPS and SOPHIE (at ESO in Chile and OHP in France) in collaboration with European astronomers. My main expertise is with the second method, the transit method, which measures the dimming of the star as a planet passes in front of it. I have already participated in the detection of transits for a dozen gaseous giant planets, as well as the only transiting Neptune-mass planet known yet (GJ 436b). I will search for new transiting rock/ice planets in data from the CoRoT space telescope, and for transits of known low-mass planets with small ground-based telescopes. The next step is to measure their properties. Uniquely powerful observations are possible when a planet transits its parent star, or passes behind it on the opposite side of the orbit, which reveal key properties such as mass, radius, bulk composition, and atmospheric temperature. The Hubble Space Telescope (HST) and Spitzer Infrared Space Telescope Facility (SIRTF) have opened up this field in the past few years. I recently led a team, which made the first detection of a high altitude haze in the atmosphere of the giant planet companion to the bright star HD 189733 using the HST, and have similar observations scheduled soon for GJ. Over the next few years, I will continue using space facilities to characterise newly identified low-mass planets. I also intend to use smaller ground-based telescopes to monitor transits of known planets. These time-critical observations are difficult to schedule at normal sites, and Antarctica, with months of uninterrupted darkness, has emerged as a promising alternative. I take part in a project to install a small telescope for transit observations at Dome C on the central Antarctic plateau, where the Exeter Astrophysics Group is already involved with a number of astronomical projects. The ultimate aim of this program is to improve our understanding of the formation, evolution and structure of rock/ice planets, by comparing the numbers and properties of different types of detected planets to what theoretical models predict. This requires accounting not only for what we see, but also for what we miss. I have investigated the biases in commonly used planet detection methods, and the degree of uncertainty on the properties we measure. I have also, with colleagues specialised in modelling stellar structure, started developing structure models for rock/ice planets, which I plan to extend by collaborating with planet formation specialists. I will then apply this to the results of the observational projects mentioned earlier to build up an end-to-end view of the statistical implications of their results.