GLOBAL MAPPING OF EARTH-LIKE EXOPLANETS FROM SCATTERED LIGHT CURVES
GLOBAL MAPPING OF EARTH-LIKE EXOPLANETS FROM SCATTERED LIGHT CURVES
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DOI：
10.1088/0004-637x/720/2/1333
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发表时间：
2010-04
期刊：
影响因子：
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通讯作者：
H. Kawahara;Y. Fujii
中科院分区：
文献类型：
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作者：
H. Kawahara;Y. Fujii
类地系外行星发出的散射光提供了有关其行星表面的宝贵信息。将Fujii等人提出的地表重建方法应用于散射光的日变化和年变化，我们开发了一种纵向和纬度分辨率的土地分布重建方法。我们发现，一个理想的类地行星的全球地图可以在以下假设下恢复：(1)无云，(2)正面朝上的圆形轨道，(3)已知的表面类型及其反射光谱，(4)缺乏大气吸收，(5)已知的自转速率，(6)静态地图，(7)没有月球。利用光曲线对行星倾角的依赖关系，我们还证明了采用χ2最小化或扩展信息判据可以测量行星倾角。我们通过将其应用于无云模式地球的多波段光度测量，如掩星臭氧观测站（O3），证明了我们方法的可行性。我们的结论是，未来的太空任务至少可以在5%的范围内估计无云的类地行星的表面分布和倾角。
Scattered lights from terrestrial exoplanets provide valuable information about their planetary surface. Applying the surface reconstruction method proposed by Fujii et al. to both diurnal and annual variations of scattered light, we develop a reconstruction method of land distribution with both longitudinal and latitudinal resolutions. We find that one can recover a global map of an idealized Earth-like planet on the following assumptions: (1) cloudlessness, (2) a face-on circular orbit, (3) known surface types and their reflectance spectra, (4) lack of atmospheric absorption, (5) known rotation rate, (6) a static map, and (7) the absence of a moon. Using the dependence of light curves on planetary obliquity, we also show that the obliquity can be measured by adopting the χ2 minimization or the extended information criterion. We demonstrate the feasibility of our methodology by applying it to a multi-band photometry of a cloudless model Earth with future space missions such as the occulting ozone observatory (O3). We conclude that future space missions can estimate both the surface distribution and the obliquity at least for cloudless Earth-like planets within 5 pc.