TOI-4468行星系统的发现与表征：一颗带有孤立邻近外层伴星的凌日热木星
Discovery and Characterization of the TOI-4468 Planetary System: A Transiting Hot Jupiter With a Lone Nearby Outer Companion
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中文总结 AI 辅助
本研究发现TOI-4468行星系统含热木星TOI-4468 b与外层亚海王星TOI-4468 c，结合多观测数据约束其参数，探讨其对热木星形成研究的意义。
中文摘要 AI 辅助
我们报告了在恒星TOI-4468周围发现两颗行星的结果：一颗热木星和一颗邻近的外层亚海王星。该系统在目前的系外行星普查中独具特色，其热木星拥有一颗邻近的外层伴星，却无伴随的内层伴星。通过联合拟合NEID摄谱仪获取的视向速度测量数据，以及TESS和多个地基天文台的凌日光度测量数据，我们约束了这两颗行星的轨道周期、质量和半径。我们确认了热木星TOI-4468 b的行星属性（半径R=1.01 R_J，质量m=0.54 M_J，轨道周期P=2.77天）；同时结合地基观测的约束，通过统计方法验证了外层行星TOI-4468 c（半径R=0.28 R_J，轨道周期P=7.01天）。我们还识别出一个额外的视向速度信号，但无法确认其真实性，该信号可能源于该系统中一颗轨道周期为624天的外层巨行星。基于该系统的观测几何结构，我们认为它从未经历过早期的长期共振，而这种共振被认为会激发其他热木星/外层伴星系统的相互倾角。我们还讨论了未被探测到的内层伴星的可能性，以及该系统对热木星形成的潜在意义。
英文摘要
We report the discovery of two planets, a hot Jupiter and a nearby outer sub-Neptune, orbiting the star TOI-4468. This system is unique among the current exoplanet census in that it features a close outer companion to a hot Jupiter without an accompanying inner companion. By jointly fitting radial velocity measurements taken with the NEID spectrograph and transit photometry from TESS and several ground-based observatories, we constrain the orbital periods, masses, and radii of these two planets. We confirm the planetary nature of the hot Jupiter TOI-4468 b ($R = 1.01 R_J$, $m = 0.54 M_J$, $P = 2.77$ days). We also validate the outer planet TOI-4468 c ($R = 0.28 R_J$, $P = 7.01$ days) statistically, incorporating constraints from ground-based observations. We also identify, but cannot confirm, an additional radial velocity signal which may be due to an outer giant in this system with an orbital period of 624 days. From the observed geometry of this system, we argue that it must never have encountered an early secular resonance that is thought to excite the mutual inclination of other hot Jupiter/outer companion systems. We discuss the possibility of an undetected inner companion, as well as potential implications for hot Jupiter formation.
