大质量恒星形成区域的磁场（MagMaR）。VIII. GGD 27吸积流中被引力超越的磁场
Magnetic fields in Massive Star-Forming Regions (MagMaR). VIII. Magnetic field overrun by gravity in GGD 27's accretion streamers
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中文总结 AI 辅助
研究GGD 27吸积流中磁场作用，通过识别吸积流、拟合轨迹、估计磁场强度及主导力，利用ALMA数据和相关方法得出吸积流亚阿尔文速度，约3000天文单位处原恒星引力阱主导气体运动，有助于理解恒星形成过程中磁场角色。
中文摘要 AI 辅助
背景。与原恒星盘和/或包层相连的吸积流被认为能在数千天文单位的距离上传输物质。构成这些吸积流的气体运动是由引力、大规模外部湍流还是磁场作用主导，仍在研究中。目的。这项工作旨在了解磁场在恒星形成过程中的作用，特别是磁力在潜在引导气体流动以及吸积到环绕原恒星的包层和盘上的作用。方法。首先，我们试图识别朝向高质量年轻恒星物体GGD 27-MM1的大规模吸积流，并使用所谓的门多萨模型拟合其轨迹，该模型是对流体粒子在势阱中纯引力下落运动的经典模型的修正。其次，我们估计与吸积流相关的磁场强度。然后，我们确定吸积流是由磁力还是离心力主导。结果。通过检查阿塔卡马大型毫米波/亚毫米波阵列（ALMA）的H₂CO数据立方体，我们能够识别出四条延伸至约7000天文单位的吸积流，并在位置-位置-速度空间中拟合其轨迹。极化连续谱发射显示磁场与吸积流轨迹良好对齐。使用戴维斯-钱德拉塞卡-费米方法，我们得出磁场强度估计值，发现吸积流是亚阿尔文速度的，并在估计了湍流、有序运动（原文未明确给出此英文，根据语境推测）、磁力和引力的能量项后，讨论了一种可能的定性情景，即在约3000天文单位的距离处，GGD 27-MM1原恒星的引力阱在吸积流气体运动中比湍流和磁力更占主导。
英文摘要
Context. Accretion streamers connected to protostellar disks and/or envelopes are thought to transport material across several thousand of au. Whether the motions of the gas comprising these streamers are dominated by gravity, large scale external turbulence or the action of magnetic fields is still under scrutiny. Aims. The aim of this work is to understand the role of the magnetic fields in the star-formation processes, in particular the role that magnetic forces have in potentially leading flows of gas and the accretion onto the envelopes and disks orbiting protostars. Methods. First, we try to identify the large-scale accretion streamers toward the high-mass Young Stellar Object GGD 27-MM1 and fit their trajectories using the so-called Mendoza's model, a modification of the classical model of pure gravitational infalling motion of fluid particles in a potential well. Second, we estimate the strength of the magnetic field associated with the streamers. Then, we determine if the streamers are dominated by magnetic or centrifugal forces. Results. Inspecting the Atacama Large Millimeter/submillimeter Array (ALMA) H$_2$CO cube we were able to identify four accretion streamers spreading up to $\sim$7,000 au and fit their trajectories in the position-position-velocity space. The polarized continuum emission reveals a good alignment of the magnetic field and the trajectory of the streamers. Using the Davis-Chandrasekhar-Fermi method, we derive estimates for the magnetic field strength, find that the streamers are sub-alfvénic, and discuss (after estimating energy terms for turbulence, ordered motions, magnetic forces and gravity) a possible qualitative scenario in which, the gravitational well of the GGD 27-MM1 protostar dominates streamer gas motions over turbulence and magnetic forces at distances of $\sim 3,000$ au.
