CHIANTE I：双星系统中四颗Ariel高优先级目标的恒星倾角测量
CHIANTE I: Obliquity Measurements of Four High-Priority Ariel Targets in Binaries
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中文总结 AI 辅助
本研究通过CHIANTE项目测量四颗双星系统中Ariel任务目标热木星的恒星倾角，修正有效温度重分界值，发现纯ZKL机制无法解释观测分布，需结合对齐与行星散射机制。
中文摘要 AI 辅助
我们展示了CHIANTE项目的首批成果：该项目利用洛厄尔发现望远镜搭载的超精密光谱仪（EXPRES），表征预计2031年发射的Ariel任务的潜在目标特征。我们报告了四颗位于双星系统中的Ariel三级热木星的Rossiter-McLaughlin测量结果，这四颗行星分别是KELT-2 Ab、KELT-3 Ab、TOI-1333 Ab和TOI-1789 Ab。\n通过对EXPRES数据、存档视向速度数据以及TESS的测光数据进行联合建模，我们发现这四颗行星都与其宿主恒星处于对齐状态，尽管这些宿主恒星的有效温度（$T_{\text{eff}}$）跨越了“重对齐分界”。此前研究发现，该分界将多星系统中的行星分为两类：围绕冷恒星的行星更倾向于对齐，而围绕热恒星的行星的恒星倾角符合各向同性分布。我们修正后的重分界有效温度为$6193\pm103$ K，与此前研究结果一致但温度更高。\n我们将该分界以上所有多星系统热木星宿主的观测恒星倾角分布，与通过恒星von-Zeipel-Kozai-Lidov（ZKL）振荡产生的预期分布进行了对比——ZKL机制常被用来解释多星系统中行星轨道错位的现象。简单的种群合成模型显示，纯ZKL种群无法复现观测到的倾角分布，尤其是我们当前观测到的对齐系统和近极系统的数量都被低估了。不过，在ZKL振荡的基础上加入对齐种群和行星-行星散射种群的贡献，能更好地描述观测到的分布。尽管如此，我们仍需要更多多星系统中行星的倾角测量数据，以更好地分辨每种机制对观测到的恒星倾角分布的贡献。
英文摘要
We present the first results from CHIANTE: a program using the EXtreme PREcision Spectrograph (EXPRES) at the Lowell Discovery Telescope to characterize potential targets of the Ariel mission, anticipated to launch in 2031. We report Rossiter-McLaughlin measurements of four Ariel tier 3 hot-Jupiters which reside in binary star systems: KELT-2 Ab, KELT-3 Ab, TOI-1333 Ab, and TOI-1789 Ab. Joint modeling of EXPRES and archival radial velocities with photometry from TESS finds all four planets to be aligned their host stars, despite the host stars spanning the $T_{\text{eff}}$ realignment break, which has been found to divide the planets in multi-star systems into two subsets: those around cool stars that are preferentially aligned, and those around hot stars that exhibit stellar obliquities consistent with isotropy. We revise the $T_{\text{eff}}$ realignment break to be $=6193\pm103$ K, consistent with, but hotter than, previous work. We compare the observed stellar obliquity distribution for all multi-star, hot-Jupiter hosts above this boundary to an expected distribution produced via stellar von-Zeipel-Kozai-Lidov (ZKL) oscillations, a mechanism often invoked to explain misaligned planets in multi-star systems. A simple population synthesis model finds that a pure ZKL population is unable to replicate the observed obliquities. In particular, both the number of aligned and near-polar systems we see today are underestimated. However, adding contributions from aligned and planet-planet scattering populations alongside ZKL oscillations better describes the observed distribution. Nonetheless, more obliquity measurements for planets in multi-star systems are needed to better discern the contributions of each mechanism the observed stellar obliquity distribution.
