热木星WASP-62b高、低分辨率透射光谱的联合反演研究
A Joint Retrieval on the High- and Low-resolution Transmission Spectra of the Hot Jupiter WASP-62b
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摘要: 热木星WASP-62b是目前已知少有的具有晴空大气特征的系外行星之一, 为研究高温气态巨行星的大气物理化学性质提供了理想样本. 该工作旨在结合地基高分辨率与空间低分辨率光谱数据, 对WASP-62b的大气参数进行联合反演研究, 以获得对其大气特性更全面的约束. 利用HARPS (High Accuracy Radial velocity Planet Searcher)光谱仪的高分辨率观测数据, 成功解析了Na双线线心, 且探测到的视向速度变化与行星轨道运动一致, 从而确认该信号源自行星大气. 进一步开展的高、低分辨率透射光谱联合反演分析表明: (1)确认WASP-62b大气中存在显著的Na原子压力致宽线翼特征, 证实其大气具有显著的晴空特征; (2)明确支持大气垂直温压3层分布, 暗示高层大气存在显著的加热过程; (3)探测到行星大气存在显著的致宽效应, 在纯旋转致宽模型假设下得到的等效旋转速度远超潮汐锁定假设下的自转速度. 该工作展示了高、低分辨率联合反演在系外行星大气刻画中的独特优势, 也为后续韦布空间望远镜的精细观测提供了重要参考.Abstract: The hot Jupiter WASP-62b is one of the few known exoplanets possessing clear-sky signatures, making it an ideal target for investigating the physical and chemical properties of hot gas giant atmospheres. This work aims to perform a joint retrieval analysis of the atmospheric parameters of WASP-62b by combining ground-based high-resolution and space-based low-resolution spectroscopic data, thereby obtaining more comprehensive constraints on its atmospheric properties. Based on high-resolution observations from the HARPS (High Accuracy Radial velocity Planet Searcher) spectrograph, the line cores of the Na doublet were successfully resolved. The detected radial velocity variation is consistent with the planetary orbital motion, confirming that the signal originates from the planetary atmosphere. Furthermore, the joint retrieval analysis of high- and low-resolution transmission spectra indicates that: (1) prominent pressure-broadened line wings of Na are present in the atmosphere of WASP-62b, confirming the presence of clear-sky regions; (2) a three-layer vertical temperature-pressure profile is explicitly supported, implying a significant heating process in the upper atmosphere; and (3) a significant broadening effect is detected, where the equivalent rotational velocity obtained under the assumption of a pure rotation broadening model far exceeds the rotation speed expected under the tidal-locking assumption. This study demonstrates the unique advantages of combining high- and low-resolution data for characterizing exoplanet atmospheres and provides an important reference for future detailed observations with the James Webb Space Telescope.
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