Lee Chin-Fei, Jhan Kai-Syun, Moraghan Anthony
Academia Sinica Institute of Astronomy and Astrophysics, No. 1, Sec. 4, Roosevelt Road, Taipei, 106319, Taiwan, ROC.
Taiwan Astronomical Research Alliance (TARA), Taipei, Taiwan, ROC.
Sci Rep. 2025 Aug 13;15(1):29702. doi: 10.1038/s41598-025-11602-w.
Protostellar jets form when part of the accreting material is energetically ejected from the vicinity of protostars. Understanding where and how they are launched and collimated is crucial to determining their role in the accretion process. The HH 211 jet is a highly collimated, magnetized jet associated with a rotating disk around a young protostar. With Atacama Large Millimeter/submillimeter Array, we have resolved a pristine molecular spine at its base down to the disk. This spine has a high velocity of ~ 107 ± 8 km s but a slow rotation with a specific angular momentum of ~ 4 ± 1 au km s, suggesting it to be launched at ~ 0.021 ± 0.005 au in the disk, providing the most stringent constraint yet on current magneto-centrifugal theories of jet production. Quantitative modeling supports the interpretation that the molecular spine represents the dense central component of a magnetized radial wind. This wind, launched by magneto-centrifugal force at the innermost edge of the disk-the truncation radius, removes residual angular momentum from the disk, enabling disk material to accrete onto the protostar. The toroidal field strength to collimate the dense spine in the model also agrees with that previously measured in the jet.
原恒星喷流是在吸积物质的一部分从原恒星附近被高能喷射时形成的。了解它们在何处以及如何发射和准直对于确定它们在吸积过程中的作用至关重要。HH 211喷流是与围绕年轻原恒星的旋转盘相关联的高度准直、磁化的喷流。利用阿塔卡马大型毫米波/亚毫米波阵列，我们在其基部直至盘区分辨出了一条原始的分子脊。这条脊具有约107±8千米每秒的高速度，但旋转缓慢，比角动量约为4±1天文单位·千米每秒，这表明它是在盘区约0.021±0.005天文单位处发射的，这为当前喷流产生的磁离心理论提供了迄今为止最严格的限制。定量建模支持了分子脊代表磁化径向风的致密中心成分的解释。这种风由盘的最内边缘——截断半径处的磁离心力发射，从盘中去除残余角动量，使盘物质能够吸积到原恒星上。模型中使致密脊准直所需的环形场强也与先前在喷流中测量的结果一致。
