摘要
系外类地行星是目前搜寻地外生命的主要目标。随着观测仪器的发展,现在已经能探测到低于10个地球质量的系外行星。该文简要回顾了系外类地行星的形成与演化,介绍了当前研究它们内部结构的模型和方法,以及由此得出的类地行星质量-半径关系。同时,对应不同的行星初始物质成分,讨论了各种可能的大气结构。最后介绍了未来的空间任务在相关方面的工作。
To date, more than 340 extrasolar planets have been discovered. These planets exhibit a plethora of diversity and have already changed our understanding of planet formation. The existence of massive terrestrial planets is predicted by planetary formation theory. Such planets are also cMled ＂Super-Earth＂ due to their masses ranging from 1 to 10M. Due to the improvements in detection methods, they are now explored through radial velocity technique. Such planets do not exist in our solar system, so they are introducing a novel physical regime that has never been investigated before. In this paper, we introduce a method by seeking the interior of Super-Earths nowadays. Based on the internal structure of Earth, the model may divide the Super-Earth planets＇ internal into several shells according to their composition. Chosen an equation of state （EOS） in relation to density, pressure, and temperature within each layer, the numerical model can solve the standard differential equations for density, pressure, mass, and gravity structure under hydrostatic equilibrium. Then we present the latest results of current research and depict the mass-radius of the Super-Earth planets. In addition, we also discuss tidal heating effect on the terrestrial planet, i.e., GJ 876d. Planets may obtain atmospheres from three main sources： capture from the nebula, degassing during accretion, and later degassing from tectonic processes. Low-mass terrestrial planets are unable to capture and retain nebula gases, so researchers focus on the range of atmospheric masses possible form degassing terrestrialanalog materials in the planetary accretion process. The Atmospheric mass and composition for terrestrial planets is closely related to the composition of a rocky planet. From the library of meteorites that have fallen to Earth, we can build up several models corresponding to various plausible starting compositions for planetary accretion and degassing. Herein we give a detailed description of each model and major results. These outcom
出处
《天文学进展》
CSCD
北大核心
2009年第4期301-315,共15页
Progress In Astronomy
基金
国家自然科学基金项目(10973044
10833001
10573040
10673006)
江苏省自然科学基金
紫金山天文台小行星基金会资助课题
国家自然科学基金国际合作项目(10911130220)
关键词
系外行星
类地行星
状态方程
内部结构
大气
extrasolar planet
terrestrial planets
equation of state
interiors
atmosphere
