文章基本信息

标题：Reflected Spectroscopy of Small Exoplanets II: Characterization of Terrestrial Exoplanets
本地全文：下载
作者：Mario Damiano ; Renyu Hu
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2022
卷号：163
期号：6
页码：1-14
DOI：10.3847/1538-3881/ac6b97
语种：English
出版社：American Institute of Physics
摘要：A space telescope capable of high-contrast imaging has been recognized as the avenue toward finding terrestrial planets around nearby Sun-like stars and characterizing their potential habitability. It is thus essential to quantify the capability of reflected light spectroscopy obtained through direct imaging for terrestrial exoplanets, and existing work focused on planetary analogs of modern Earth. Here we go beyond Earth analogs and use a Bayesian retrieval algorithm, ExoReL, to determine what we could learn about terrestrial exoplanets from their reflected light spectra. Recognizing the potential diversity of terrestrial exoplanets, our focus is to distinguish atmospheric scenarios without any a priori knowledge of the dominant gas. We find that, while a moderate-resolution spectrum in the optical band (0.4−1.0 μm) may sufficiently characterize a modern Earth analog, it would likely result in incorrect interpretation for planets similar to Archean Earth or having CO2-dominated atmospheres. Including observations in the near-infrared bands (1.0−1.8 μm) can prevent this error, determine the main component (N2, O2, or CO2), and quantify trace gases (H2O, O3, and CH4) of the atmosphere. These results are useful to define the science requirements and design the wavelength bandwidth and observation plans of exoplanet direct imaging missions in the future.