Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei, 106, Taiwan.
Graduate Institute of Astronomy and Astrophysics, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan.
Nat Commun. 2018 Nov 6;9(1):4636. doi: 10.1038/s41467-018-07143-8.
Protostellar jets are one of the most intriguing signposts in star formation. Recent detection of a jet rotation indicates that they can carry away angular momenta from the innermost edges of the disks, allowing the disks to feed the central protostars. In current jet-launching models, magnetic fields are required to launch and collimate the jets, however, observationally, it is still uncertain if magnetic fields are really present in the jets. Here we report a clear detection of SiO line polarization in the HH 211 protostellar jet. Since this line polarization has been attributed to the Goldreich-Kylafis effect in the presence of magnetic field, our observations show convincingly the presence of magnetic field in a jet from a low-mass protostar. The implied magnetic field could be mainly toroidal, as suggested in current jet-launching models, in order to collimate the jet at large distances.
原恒星喷流是恒星形成中最引人注目的标志之一。最近对喷流旋转的探测表明，它们可以从磁盘的最内边缘带走角动量，从而使磁盘能够为中心原恒星提供物质。在当前的喷流发射模型中，需要磁场来发射和准直喷流，然而，在观测上，仍然不确定喷流中是否真的存在磁场。在这里，我们报告了在 HH 211 原恒星喷流中清晰地探测到了 SiO 线偏振。由于这种线偏振归因于磁场存在时的 Goldreich-Kylafis 效应，我们的观测令人信服地表明，在一个来自低质量原恒星的喷流中存在磁场。所暗示的磁场可能主要是环形的，如当前的喷流发射模型所建议的，以在大距离处准直喷流。
