Imaging Discovery of Other Worlds Around Nearby Stars

在过去的20年里，已知的系外行星数量呈指数级增长，接近1000颗。这些系外行星中的绝大多数轨道非常接近它们的主星星（所谓的热彗星），但其中一些是低质量的地球大小的行星，围绕低质量恒星运行，可能在系统的可居住区，那里可能存在液态水和我们所知的生命。虽然这些发现非常令人兴奋，但我们对这些系外行星的了解仍然非常有限，因为它们中的绝大多数都是使用间接技术发现的。需要详细的光度学和光谱学来正确表征行星，但由于现有仪器的限制，迄今为止只对少数行星进行了详细的分析。** 直接系外行星成像技术仍然是表征系外行星的最简单方法。当直接探测到行星的光时，摄谱仪可用于：研究行星的大气成分;估计其大气温度/光度;评估其表面重力;研究云的影响，对于岩石行星;寻找生命迹象。直接的系外行星成像是一项具有挑战性的奋进，因为小的星星/行星角间距和主星星与行星之间的大光度比，从温暖的年轻类地行星的10万倍到类地行星的数百亿倍。** 经过10年的开发，第一批专用的、设施级的、高度优化的系外行星成像仪器正在运往天文台。我的团队（也是双子座行星成像仪GPI的建造团队）已经在GPI上获得了900小时的观测时间，用于附近600颗恒星的活动，以寻找和描述大约50颗新的温暖的类木星行星（比目前成像的多10倍）。GPI将通过使用星光阻挡掩模和精确的波前控制，实现比现有仪器深100倍的对比度，从而获得年轻和附近行星系统的独特视图。这个NSERC发现补助金将使我能够资助两名研究生，他们将加入GPI团队进行这一令人兴奋的冒险。学生可以获取，减少和分析GPI数据，帮助组织活动和/或执行详细的分析，如轨道拟合，多行星系统的稳定性研究和搜索由变化的云层覆盖产生的光度/光谱时间变化。他们的部分时间将被分配用于进一步开发图像减影算法和研究仪器的可能升级。** 学生还将参与未来系外行星成像工具的设计过程，为计划中的30米望远镜（TMT）和空间系外行星成像望远镜（MAPLE）进行数值模拟。TMT是目前处于设计/建造阶段的下一代超大型望远镜的一部分，其孔径比现有设施增加了3倍。TMT将实现无与伦比的分辨率，允许直接成像太阳系尺度的木星行星（< 10天文单位（Au），即10倍地球-太阳分离）。通过学生们将帮助构思的优化仪器，甚至有可能直接成像最近的低质量恒星周围的类地行星。MAPLE项目是由我领导的一个新的太空望远镜概念。学生们将分析这台直径为50厘米的可见波段太空望远镜的性能，以便在最近的恒星周围直接成像，在最近的恒星周围轨道上的超级地球/冰巨行星的反射光。** 通过研究这些概念获得的专门知识将适用于未来的观测站，这些观测站有一天将拍摄类似地球的行星。

Over the past 20 years, the number of known exoplanets has grown exponentially to close to 1,000. The vast majority of these exoplanets orbit very close to their primary star (the so called hot Jupiters), but a few of them are low mass Earth-size planets in orbit around lower mass stars, possibly in the systems' habitable zones where liquid water, and life-as-we-know-it, could exist. While those discoveries are very exciting, what we know about these exoplanets is still very limited, as the vast majority of them have been discovered using indirect techniques. Detailed photometry and spectroscopy are needed to properly characterize planets, but this detailed analysis has only been conducted on a few to date due to limitations of existing instrumentation. **The direct exoplanet imaging technique remains the simplest way to characterize an exoplanet. When the light of a planet is directly detected, a spectrograph can be used to: study the planet atmospheric composition; estimate its atmospheric temperature/luminosity; evaluate its surface gravity; study the effect of clouds and, for rocky planets; find signs of life. Direct exoplanet imaging is a challenging endeavor due to the small star/planet angular separation and large luminosity ratio between the host star and the planet, from 100,000 times fainter for a warm young Jupiter-like planet to tens of billion of times fainter for an Earth-like planet. **After 10 years of development, a first wave of dedicated, facility-class, highly-optimized exoplanet imaging instruments is being shipped to observatories. My team (also the building team of the Gemini Planet Imager, GPI) has secured 900h of observing time on GPI for a nearby 600 stars campaign to find and characterize approximately 50 new warm Jupiter-like planets (10 times more than currently imaged). GPI will achieve 100x deeper contrast than existing instruments by the use of a starlight blocking mask and precise wavefront control, allowing a unique view of young and nearby planetary systems.**This NSERC Discovery grant will enable me to fund two graduate students that will join the GPI team for this exciting adventure. The students may acquire, reduce and analyze GPI data, help organize the campaign and/or perform detailed analyses, such as orbit fitting, stability studies for multi-planet systems and search for photometric/spectroscopic time variations generated by changing cloud cover. Part of their time will be allocated to further develop the image subtraction algorithms and study possible upgrades to the instrument. **The students will also participate in the design process of their future exoplanet imaging tools, by performing numerical simulations for the planned Thirty Meter Telescope (TMT) and a space exoplanet imaging telescope (MAPLE). The TMT is part of the next generation of extremely large telescopes currently in the designing/building stage, representing a 3x increase in aperture to current facilities. The TMT will achieve unparalleled resolution, allowing to directly image Jovian planets at solar system scale (< 10 astronomical units (AU), i.e. 10x the Earth-Sun separation). With optimized instruments that the students will help conceive, it may even be possible to directly image Earth-like planets around the nearest low mass stars. The project MAPLE is a new Canadian-led space telescope concept that I am leading. The students will analyze the performance of this 50 cm diameter visible-band space telescope to directly image, around the nearest stars, the reflected light of super-Earth/ice giant planets in orbit around the nearest stars. **The expertise gained by studying those concepts will be applicable to future observatories that will one day take a picture of an Earth-like planet.