发表机构
School of Astronomy and Space Science, Nanjing University; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（南京大学天文与空间科学学院; 教育部现代天文学与天体物理重点实验室（南京大学））
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用多点速度色散函数（VDF）方法分析天鹅座X分子云数据，识别出10个子结构，发现约2-5秒差距的湍流相关尺度，并表明VDF能更稳健地约束该尺度。
AI 中文摘要
湍流在调节分子云内的恒星形成活动中起着至关重要的作用，然而很少有方法能够直接揭示其性质和潜在过程。我们利用野边山45米望远镜天鹅座X CO巡天的分子谱线数据来研究湍流性质及其与恒星形成活动和/或其他非热运动的关联。在本工作中，我们应用多点速度色散函数（VDF），而非直接的谱线宽度测量，来研究分子云运动的非热性质。我们滤除大尺度有序结构，并分离出相对小尺度的湍流分量。通过速度中的朋友（FIVe）算法，我们识别出云的10个子结构，并使用VDF方法推导出每朵云的湍流性质。我们发现，无论是云复合体区域还是这10个速度子结构，都表现出约2--5秒差距的湍流相关长度。这一平台尺度暗示了天鹅座X中存在秒差距尺度的湍流相关或驱动尺度。在此尺度以下，上升的VDF追踪了湍流级联的速度标度律，而更大尺度的VDF变化可能反映了云尺度运动。云复合体与子结构之间的比较进一步表明，在观测数据中，VDF可能比湍流速度色散更稳健地约束湍流相关尺度。
英文摘要
Turbulence plays a crucial role in regulating star formation activities within molecular clouds, yet few methods can directly reveal its properties and underlying processes. We use molecular line data from the Nobeyama 45m Cygnus X CO Survey to study the turbulence properties and their relationships with star-forming activities and/or other non-thermal motions. In this work, we apply the multi-point velocity dispersion function (VDF), rather than direct linewidth measurements, to investigate the non-thermal properties of molecular cloud motions. We filter out the large-scale ordered structure and isolate a relatively small-scale turbulence component. Through the Friends In Velocity (FIVe) algorithm, we identify 10 substructures of the clouds and derive the turbulent properties of each cloud using the VDF method. We find that both the cloud-complex regions and the 10 velocity substructures exhibit turbulence correlation lengths of $\sim 2$--5 pc. This plateau scale suggests a parsec-scale turbulence correlation or driving scale in Cygnus X. Below this scale, the rising VDFs trace the velocity scaling of the turbulent cascade, whereas larger-scale VDF variations likely reflect cloud-scale motions. The comparison between cloud complexes and substructures further suggests that, in observational data, the VDF may constrain the turbulence correlation scale more robustly than the turbulence velocity dispersion.
Comments17 pages, 9 figures, 2 tables. Accepted for publication in The Astrophysical Journal
