TESS-Keck巡天. XII. 一颗密度较高的1.8 R$_\oplus$超短周期行星在首个Gyr后可能仍保留着高分子量大气
The TESS-Keck Survey. XII. A Dense 1.8 R$_\oplus$ Ultra-Short-Period Planet Possibly Clinging to a High-Mean-Molecular-Weight Atmosphere After the First Gyr
AI总结：
本文确认并表征了超短周期行星TOI-1347 b，其质量和半径表明具有类地成分，且光蒸发已结束；TESS数据中探测到的相位曲线变化和次食暗示其可能保留着高分子量大气。
摘要：
超短周期行星（USPs）的极端环境是研究系外行星如何获得、失去、保留和/或重新获得气体大气的绝佳实验室。我们确认并表征了USP TOI-1347 b，这是一颗半径为1.8 ± 0.1 R$_\oplus$、轨道周期为0.85天的行星，由TESS任务的测光数据探测到。我们使用Keck/HIRES和HARPS-N测量了TOI-1347系统的径向速度，发现该USP异常巨大，质量为11.1 ± 1.2 M$_\oplus$。测得的质量和半径表明TOI-1347 b具有类似地球的整体成分。可以高置信度排除存在薄H/He包层（质量占比>0.01%）。该系统年龄在1至1.8 Gyr之间；因此，强烈的光蒸发应该已经结束。我们在TESS测光数据中探测到暂定的相位曲线变化（3σ）和次食（2σ），若被证实，可能表明存在高分子量大气。我们建议进行额外的光学和红外观测以确认大气的存在并研究其成分。
英文摘要：
The extreme environments of ultra-short-period planets (USPs) make excellent laboratories to study how exoplanets obtain, lose, retain, and/or regain gaseous atmospheres. We present the confirmation and characterization of the USP TOI-1347 b, a $1.8 \pm 0.1$ R$_\oplus$ planet on a 0.85 day orbit that was detected with photometry from the TESS mission. We measured radial velocities of the TOI-1347 system using Keck/HIRES and HARPS-N and found the USP to be unusually massive at $11.1 \pm 1.2$ M$_\oplus$. The measured mass and radius of TOI-1347 b imply an Earth-like bulk composition. A thin H/He envelope (>0.01% by mass) can be ruled out at high confidence. The system is between 1 and 1.8 Gyr old; therefore, intensive photoevaporation should have concluded. We detected a tentative phase curve variation (3$σ$) and a secondary eclipse (2$σ$) in TESS photometry, which if confirmed could indicate the presence of a high-mean-molecular-weight atmosphere. We recommend additional optical and infrared observations to confirm the presence of an atmosphere and investigate its composition.
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