High Spatial and Spectral Resolution Images of Titan at Infrared Wavelenths: Observations and Analysis

AST 0205893dePaterDR.加州大学伯克利分校的伊姆克·德帕特将指导一个关于土卫六的地面高分辨率成像、光谱分析和建模的项目。该计划将使用一些世界上最大的光学/红外望远镜，10米长的凯克天文台和8米长的双子座望远镜，在1到2.5微米波长的窄带滤光片中获取土卫六的衍射限制图像。为了更详细地研究土卫六的大气层和表面，迪帕特博士和她的团队将使用近红外光谱仪NIR-SPEC和凯克自适应光学系统获得土卫六的光谱图像数据立方体。土卫六的光谱不会立即揭示土卫六的表面成分，因为从土卫六表面反射的太阳光将部分被土卫六大气中的甲烷气体(以及其他吸收体)吸收，并将经历雾霾颗粒的散射。由于土卫六的表面反照率在其表面上差异很大，对土卫六的一次观测并不能给出必要的限制来确定大气雾霾和甲烷云的分布和性质。为了更好地约束土卫六的大气层和表面，该团队将通过多条大气路径观察相同的表面特征。同时，该团队将开发土卫六大气的高级模型，以同时提取土卫六表面反射光谱和垂直雾霾分布作为土卫六圆盘位置的函数。为了更好地了解大气雾霾粒子的形成和清除过程，以及它们的化学和物理性质，该小组将通过对中红外波长的观测来补充数据，中红外波长对土卫六的高海拔雾霾和各种碳氢化合物气体非常敏感。

AST 0205893dePaterDr. Imke dePater, of the University of California at Berkeley, will direct a program of ground-based high resolution imaging, spectroscopy, and modeling of Titan. The program will use some of the world's largest optical/infrared telescopes, the 10-m Keck Observatory and the 8-m Gemini Telescope, to obtain diffraction-limited images of Titan in narrow band filters between 1 and 2.5 micron wavelength. To investigate Titan's atmosphere and surface in even greater detail, Dr. dePater and her team will obtain spectral image datacubes of Titan using the near-infrared spectrometer NIR-SPEC together with the Keck Adaptive Optics system. Spectra of Titan will not immediately reveal surface composition, since sunlight reflected from the surface will in part be absorbed by methane gas (as well as other absorbers) in Titan's atmosphere, and will undergo scattering by haze particles. Since Titan's surface albedo varies significantly across its surface, a single observation of Titan does not give the necessary constraints to determine the atmospheric haze and methane cloud distribution and properties. To better constrain Titan's atmosphere and surface, this team will observe the same surface features through multiple atmospheric paths. In parallel the team will develop advanced models of Titan's atmosphere, to simultaneously extract surface reflectance spectra and the vertical haze distribution as a function of location on Titan's disk. To better understand the formation and removal processes of the atmospheric haze particles, as well as their chemical and physical properties, this group will complement the data with observations at mid-infrared wavelengths, sensitive to Titan's high-altitude hazes and various hydrocarbon gases.***