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标题：Contrast and Temperature Dependence of Multi-epoch High-resolution Cross-correlation Exoplanet Spectroscopy
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作者：Luke Finnerty ; Cam Buzard ; Stefan Pelletier 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2021
卷号：161
期号：3
页码：1-17
DOI：10.3847/1538-3881/abd6ec
语种：English
出版社：American Institute of Physics
摘要：While high-resolution cross-correlation spectroscopy (HRCCS) techniques have proven effective at characterizing the atmospheres of transiting and nontransiting hot Jupiters, the limitations of these techniques are not well understood. We present a series of simulations of one HRCCS technique, which combines the cross-correlation functions from multiple epochs, to place temperature and contrast limits on the accessible exoplanet population for the first time. We find that planets approximately Saturn-sized and larger within ∼0.2 au of a Sun-like star are likely to be detectable with current instrumentation in the L band, a significant expansion compared with the previously studied population. Cooler (Teq ≤ 1000 K) exoplanets are more detectable than suggested by their photometric contrast alone as a result of chemical changes that increase spectroscopic contrast. The L-band CH4 spectrum of cooler exoplanets enables robust constraints on the atmospheric C/O ratio at Teq ∼ 900 K, which have proven difficult to obtain for hot Jupiters. These results suggest that the multi-epoch approach to HRCCS can detect and characterize exoplanet atmospheres throughout the inner regions of Sun-like systems with existing high-resolution spectrographs. We find that many epochs of modest signal-to-noise ratio (S/Nepoch ∼ 1500) yield the clearest detections and constraints on C/O, emphasizing the need for high-precision near-infrared telluric correction with short integration times.