Direct detection and characterization of extrasolar planets

我们建议使用高角分辨率和高动态范围成像来研究系外行星和附近恒星周围的尘埃碎片盘。我们将重点放在双子座行星成像仪(GPI)上，这是一种“极端”的自适应光学日冕仪，将拍摄围绕太阳附近恒星运行的自发光系外行星的图像。这项任务的第一阶段包括与GPI一起准备和执行系外行星调查。虽然最年轻的恒星(100Myr)是最好的目标，但GPI对年龄在2 Gyr以下的系外行星有很好的敏感性。这些“年轻”的寄宿恒星比它们年轻的表亲要多得多，因此它们很重要，因为它们提供了描述行星人口的必要的统计数据。虽然在100pc以内的大多数年轻恒星已经被定位，但只有一小部分&lt；2Gyr恒星被发现。我们将通过对大约1500颗恒星的光谱调查来识别年轻恒星并限制它们的年龄。我们将测量CaII H&K和Li I 6707ä谱线强度，以及恒星vsin I和径向速度。这项调查的第二阶段涉及用GPI进行实际观测，以确定候选系外行星。我们将进行三项核心调查：1)确定行星系统的丰度；2)对气体巨星只能通过引力不稳定形成的区域进行普查，以检验核心吸积模型；3)通过寻找向外迁移的行星来阐明热木星的起源；4)显示我们自己的行星系统的结构是否独特。第三阶段包括利用天体测量学和光谱学对发现的候选者进行确认和表征。一旦确认了物理关联，最后阶段包括大气属性(有效温度、重力和组成)的测量和轨道要素的初步估计。拟议工作的每一部分都旨在吸引最优秀的学生从事研究生研究，并让他们参与到最高级别的研究中；计划该项目将产生四篇博士论文。

We propose to study exoplanets and dusty debris disks around nearby stars using high angular resolution and high dynamic range imaging. We focus on the Gemini Planet Imager (GPI) instrument, which is an "extreme" adaptive optics coronagraph that will image self-luminous exoplanets orbiting stars in the solar neighborhood. The first stage of this task includes preparation for and execution of exoplanet surveys with GPI. Although the youngest stars (<100 Myr) are the best targets, GPI has good sensitivity to exoplanets with ages up to 2 Gyr. These "adolescent" host stars are more numerous than their youthful cousins and therefore they are important because they offer the statistical riches necessary to characterize planet populations. Although the majority of young stars within 100 pc have been located, a much smaller fraction of < 2 Gyr stars have been identified. We will pursue the identification of young stars and constrain their ages in a spectroscopic survey of about 1500 stars. We will measure Ca II H&K and Li I 6707 Å line strengths, as well as stellar v sin i and radial velocities. The second stage of this investigation involves actual observing with GPI to identify candidate exoplanets. We will conduct three core surveys that will: 1) establish the abundance of planetary systems; 2) test the core accretion model by conducting a census of regions where gas giants can only form via gravitational instability; 3) shed light on the origin of hot Jupiters by finding planets that migrated outwards; 4) show whether or not the architecture of our own planetary system is unique. The third stage involves confirmation and characterization of the candidates found using astrometry and spectroscopy. Once physical association has been confirmed the final phase involves measurement of atmospheric properties (effective temperature, gravity, and composition) and preliminary estimates of orbital elements. Each part of the proposed work is designed to attract the best students to pursue graduate research and engage them at the highest levels; it is planned that four PhD thesis will result from this program.