发表机构
Purple Mountain Observatory, Chinese Academy of Sciences; China Three Gorges University; University of Science and Technology of China（中国科学院紫金山天文台; 三峡大学; 中国科学技术大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用年轻经典造父变星样本，比较R19与X23旋臂模型，发现最年轻恒星分布支持多臂结构，更新模型改善南部旋臂约束。
AI 中文摘要
利用985颗年龄小于100 Myr的经典造父变星，我们通过将其空间和运动学分布与R19（四臂）和X23（多臂）旋臂模型进行比较，研究了银河系的大规模旋臂结构。两种模型均能对当前样本提供合理描述：R19给出的点到臂距离略小，而X23的支持臂比例更高，但描述性统计并未提供两者之间的决定性偏好。依赖于模型的臂分配和重新拟合表明，最年轻的经典造父变星（20–60 Myr）的分布与类似X23的多臂结构一致，其中英仙臂和天鹅臂形成两条主要内臂，延伸至银河棒的两端，人马臂和半人马臂段可能是这些内臂的分支，而本地臂、外臂及其他特征构成额外的臂段。更新后的模型改善了对南部旋臂结构的约束，给出了更小的点到臂距离和更高的支持臂比例。其中一些结构延伸至约15 kpc的日心距离。
英文摘要
Using 985 classical Cepheids younger than 100 Myr, we investigate the large-scale spiral structure of the Milky Way by comparing their spatial and kinematic distributions with the R19 (four-arm) and X23 (multiple-arm) spiral-arm models. Both models provide reasonably good descriptions of the current sample: R19 yields slightly smaller point-to-arm distances, whereas X23 has a higher supported-arm fraction, but the descriptive statistics do not provide a decisive preference between them. Model-dependent arm assignment and refitting suggest that the distribution of the youngest Classical Cepheids (20--60 Myr) is consistent with an X23-like multiple-arm in which the Perseus and Norma arms form two dominant inner arms extending toward the ends of the Galactic bar, the Sagittarius and Centaurus segments are possible branches of these inner arms, and Local, Outer, and other features constitute additional arm segments. The updated model improves the constraints on the southern spiral structure, yielding smaller point-to-arm distances and a higher supported-arm fraction. Some of these structures extend to heliocentric distances of approximately 15~kpc.
Comments15 pages, 5 figures; Published in ApJL
