标题： 与MAROON-X揭示的对齐次海王星以及小行星的对齐趋势 显示英文标题

标题： An Aligned Sub-Neptune Revealed with MAROON-X and a Tendency Towards Alignment for Small Planets

摘要： 我们展示了使用MAROON-X对亚海王星TOI-1759A b的Rossiter-McLaughlin测量。与MuSCAT3测光数据和九次额外的TESS凌日数据联合分析得出天空投影的偏角为$|\lambda|$=$4^\circ\pm18^{\circ}$。我们还推导出真实的偏角为$\psi$=24$\pm12^{\circ}$，使该行星与完全对齐一致，尽管是到$<1\sigma$。具有18.85天的周期和40的$a/R_{*}$，TOI-1759A b是已测量偏角的最长周期单一亚海王星。它加入了越来越多的较小行星，这些行星已经进行了此测量，并且与K2-25 b一起，是目前唯一已知的单一且对齐的亚海王星。 我们还提供了对行星偏心率测量分布的概述，这些行星的半径为 R$<8$ R$_{\oplus}$。 我们发现这类行星倾向于对齐，特别是亚海王星和超级地球，这表明其形成历史是动态冷却的。 该类别中不对齐的行星大部分具有 4$<$R$\leq$8 R$_{\oplus}$，并且比处于紧凑系统中的行星更可能是孤立的。 我们发现这一结果在$3\sigma$水平上具有显著性，与之前的研究一致。 此外，我们在可用的档案径向速度数据上进行了注入和恢复测试，以限制这些系统中大伴星的存在。 目前的档案数据对于大多数系统来说不足以检测到巨行星。 显示英文摘要

摘要： We present the Rossiter-McLaughlin measurement of the sub-Neptune TOI-1759A b with MAROON-X. A joint analysis with MuSCAT3 photometry and nine additional TESS transits produces a sky-projected obliquity of $|\lambda|$= $4^\circ\pm18^{\circ}$. We also derive a true obliquity of $\psi$=24$\pm12^{\circ}$ making this planet consistent with full alignment albeit to $<1\sigma$. With a period of 18.85 days and an $a/R_{*}$ of 40, TOI-1759A b is the longest period single sub-Neptune to have a measured obliquity. It joins a growing number of smaller planets which have had this measurement made and, along with K2-25 b, is the only single, aligned sub-Neptune known to date. We also provide an overview of the emerging distribution of obliquity measurements for planets with R$<8$ R$_{\oplus}$. We find that these types of planets tend toward alignment, especially the sub-Neptunes and super-Earths implying a dynamically cool formation history. The majority of misaligned planets in this category have 4$<$R$\leq$8 R$_{\oplus}$ and are more likely to be isolated than planets rather than in compact systems. We find this result to be significant at the $3\sigma$ level, consistent with previous studies. In addition, we conduct injection and recovery testing on available archival radial velocity data to put limits on the presence of massive companions in these systems. Current archival data is insufficient for most systems to have detected a giant planet.