AI 中文总结
本研究用ALMA观测6个红外暗枢纽-纤维系统，开发mwydyn代码分析N₂H⁺数据，发现外围宁静纤维向高动态枢纽汇聚，质心速度分布与团块质量无关，揭示枢纽中心复杂运动学的成因。
AI 中文摘要
枢纽-纤维系统是由汇聚的星际纤维组成的网络，其中心常存在活跃的恒星形成，可能在大质量恒星形成中发挥重要作用。Anderson等人（2021）发现，在红外暗枢纽中，最终形成团块中最致密核心的质量占比显著高于红外明亮团块，这表明最致密核心形成较早。这种早期大质量核心形成需要高流入率和动态活跃的红外暗团块。我们现在呈现用ALMA 12m+7m+TP设备以约3''分辨率测绘的6个红外暗枢纽-纤维系统的N₂H⁺(J=1-0)观测结果，以追踪致密气体的运动学。数据显示出复杂的发射结构和光谱。为表征其运动学，我们开发了mwydyn，一种全自动多速度分量超精细线拟合代码。我们的结果表明，发射始终由外围的宁静单个纤维组成，这些纤维向枢纽中心汇聚，在枢纽中心观测到速度弥散和分量数量的系统性增加。我们还发现，尽管团块质量跨度超过一个数量级，但其质心速度分布却非常相似。我们提出，我们的结果最好由引力驱动的多方向流入混合来解释，这导致了高度复杂和动态的枢纽中心。我们还讨论了观测到的纤维和枢纽气体运动学差异在枢纽-纤维系统三维形态背景下的意义。
英文摘要
Hub-filament systems are networks of converging interstellar filaments, often with active star formation at their centres, that may play an important role in high-mass star formation. In Anderson et al. (2021) we found that the mass fraction that ends up in a clump's most massive core is significantly higher in IR-dark hubs than IR-bright clumps, suggesting that the most-massive cores form early on. Such early massive core formation requires large inflow rates and dynamically active IR-dark clumps. We now present N$_2$H$^+$(J=1-0) observations of six IR-dark hub-filament systems mapped with ALMA 12m+7m+TP at $\sim 3''$ resolution, to trace the kinematics of the dense gas. The data show intricate emission structures and complex spectra. To characterise their kinematics, we have developed mwydyn, a fully-automated, multiple velocity component, hyperfine line-fitting code. Our results reveal that the emission invariably consists of quiescent individual filaments in the outskirts that converge towards the hub centres where a systematic increase in velocity dispersion and number of components is observed. We also find that the distribution of centroid velocities is remarkably similar between clumps, despite spanning more than one order of magnitude in mass. We propose that our results are best explained by the mixing of gravitationally-driven multi-directional inflows, resulting in highly complex and dynamic hub centres. We also discuss the implications of the observed differentiated filament and hub gas kinematics in the context of the 3D morphology of hub-filament systems.
Comments27 pages, 19 figures, submitted to MNRAS
