Comparative Exoplanetology: Ground-Based Observations of the Atmospheres of Transiting Exoplanets

随着被探测到的太阳系外行星的数量不断增加，一个特定的子集为详细研究太阳系外行星本身的性质提供了独特的机会。凌日系外行星的透射光谱是通过比较凌日期间和非凌日期间的观测结果获得的，可用于直接测量系外行星及其大气层或外逸层的有效半径。强光学跃迁中的这种测量（例如，Na I，K I）可以用来测量大气金属丰度、凝结体的雨出、恒星通量分布以及大气组分的光电离。在这里，雷德菲尔德博士和他的团队将建立在他们通过透射光谱探测凌日系外行星的第一个大气层的成功基础上。德克萨斯大学奥斯汀分校麦克唐纳天文台的9.2米Hobby Eberly望远镜最近获得了大量的调查时间，将用于将他们的计划扩展到其他几个明亮的过境系外行星。 这项大规模的观测计划是一项重大的任务，需要对数据简化和分析作出重大的承诺。必须解决的重要问题包括大地光谱的去除、连续体和恒星线核心之间差异恒星边缘暗化贡献的模型以及系统误差贡献的评估，该项目的主要目标是测量几个凌日系外行星的完整光学透射光谱，并使第一次比较研究的行星外大气性质来自传输光谱。由此产生的观测数据库将非常丰富，并将导致几个辅助研究计划以外的透射光谱，包括恒星变率监测，反射光搜索，和恒星金属丰度测量。为了帮助传播的结果，麦克唐纳天文台教育和公众外联办公室将与雷德菲尔德博士创建一系列的年度研讨会。这些讲习班将为从全国申请者中选出的15名中学教师设计，并将向他们介绍与太阳系外行星、其大气层以及用于研究它们的高光谱分辨率观测有关的科学问题。还将进行广泛的讲习班后评价，以评估将讲习班上制定的活动落实到课堂上的效果。

As the number of detected extrasolar planets continues to rise, a particular subset provides unique opportunities for detailed investigations into the properties of the extrasolar planets themselves. The transmission spectrum of a transiting exoplanet, obtained by the comparison of observations taken in-transit with those taken out-of-transit, can be used to directly measure the effective radius of the exoplanet and its atmosphere or exosphere. Such measurements in strong optical transitions (e.g., Na I, K I) can be used to measure the atmospheric metallicity, rainout of condensates, distribution of stellar flux, and photoionization of atmospheric constituents. Here, Dr. Redfield and his team will build upon their success in detecting the first atmosphere of a transiting exoplanet via transmission spectra. A recently granted large block of survey time on the 9.2-m Hobby Eberly telescope at the McDonald Observatory of the University of Texas at Austin will be used to expand their program to several other bright transiting exoplanets. This large-scale observational program is a major undertaking, and will require a nontrivial commitment to data reduction and analysis. Important issues that must be addressed include the removal of the telluric spectrum, a model of the contribution of differential stellar limb-darkening between the continuum and the cores of stellar lines, and an assessment of the contribution of systematic errors.The main objective of this project is to measure the full optical transmission spectrum for several transiting exoplanets, and enable the first comparative study of exoplanetary atmospheric properties derived from transmission spectra. The resulting observational database will be very rich and will lead to several auxiliary research programs other than transmission spectroscopy, including stellar variability monitoring, reflected light searches, and stellar metallicity measurements.To aid in the dissemination of the results, the McDonald Observatory Education and Public Outreach Office will work with Dr. Redfield to create a series of annual workshops. These workshops will be designed for fifteen secondary school teachers selected from a nationwide applicant pool, and will introduce them to the scientific issues related to extrasolar planets, their atmospheres, and the high spectral resolution observations used to study them. An extensive post-workshop evaluation will also take place in order to assess the effectiveness of the translation of activities developed in the workshop to the classroom.