由年轻星团群追踪的太阳近邻区域的分段螺旋结构
The segmented spiral structure of the Solar neighbourhood traced by young clustered populations
AI总结：
该研究通过分析年轻疏散星团与年轻恒星天体群组，结合贝叶斯高斯混合模型和最小生成树，发现太阳近邻年轻结构为分段螺旋状而非连续旋臂。
AI中文摘要：
银河系的螺旋图案仍缺乏精确约束，而太阳近邻区域最年轻的示踪天体并不总是遵循几条平滑、连续的对数旋臂。我们分析年轻疏散星团，既单独分析也结合基于年轻恒星天体（YSO）的群组，以检验它们是否定义了连续的旋臂脊或更短、部分连接的结构。在（θ_G, ln R_G）平面中，我们使用密度支持的贝叶斯高斯混合模型（BGMM）识别局部 overdensities，仅在之后引入已发表的英仙座、本地、人马座和盾牌座旋臂轨迹作为参考曲线。接着我们在日心（X,Y）平面中应用最小生成树（MST）分析以检验空间连通性。疏散星团样本已解析为几个局部成分，而加入基于YSO的群组则突出了分支和中间区域，未形成连续旋臂。MST在小修剪尺度下显示出明显的局部分支，随着连接尺度增大逐渐合并。本地-人马座区域在两种诊断方法间呈现最清晰的一致性：BGMM在参考旋臂间识别出一个中间成分，而MST通过同一区域连接相邻分支。总体而言，太阳附近的年轻结构呈现为碎片化、类螺旋的分段结构，带有部分连接，而非几条宏伟设计旋臂的平滑延续。要确定这种形态是否反映旋臂形成机制或后续演化，将需要额外的年龄、垂直和运动学信息。
英文摘要：
The Milky Way spiral pattern remains poorly constrained, and the youngest tracers in the solar neighbourhood do not always follow a few smooth, continuous logarithmic arms. We analyse young open clusters, both independently and combined with young stellar object (YSO)-based groups, to test whether they define continuous spiral-arm ridges or shorter, partially connected structures. In the (theta_G, ln R_G) plane, we identify local overdensities using a density-supported Bayesian Gaussian Mixture Model (BGMM), introducing published Perseus, Local, Sagittarius, and Scutum arm tracks only afterwards as reference curves. We then apply a Minimum Spanning Tree (MST) analysis in the heliocentric (X,Y) plane to examine spatial connectivity. The open-cluster sample already resolves into several local components, while the addition of YSO-based groups highlights branches and intermediate regions without producing continuous arms. The MST likewise shows distinct local branches at small pruning scales that progressively merge as the linking scale increases. The Local--Sagittarius region provides the clearest agreement between both diagnostics: the BGMM identifies an intermediate component between the reference arms, while the MST connects neighbouring branches through the same region. Overall, young structures near the Sun appear as fragmented, spiral-like segments with partial links rather than smooth continuations of a few grand-design arms. Determining whether this morphology reflects spiral-arm formation mechanisms or subsequent evolution will require additional age, vertical, and kinematic information.
