arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2303.07628astro-ph.GAastro-ph.SR
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马头星云中的磁场

Magnetic fields in the Horsehead Nebula

Jihye Hwang, Kate Pattle, Harriet Parsons, Mallory Go, Jongsoo Kim

AI总结:

本文利用JCMT的POL-2偏振计首次测量马头星云两个亚毫米波源的磁场,发现其磁场有序且强度足以抵抗引力坍缩,并提出了整体磁场结构模型。

摘要:

我们首次展示了马头星云的偏振尘埃辐射测量结果,这些数据是利用詹姆斯·克拉克·麦克斯韦望远镜(JCMT)上的亚毫米波通用热辐射计阵列2(SCUBA-2)相机所搭载的POL-2偏振计获得的。马头星云包含两个亚毫米波源:一个光解离区(PDR;SMM1)和一个无星核(SMM2)。我们在两个源中都观测到了排列有序的磁场。我们估算出SMM1和SMM2的平面天空磁场强度分别为56±9 μG和129±21 μG,并得到质量-磁通量比和阿尔文马赫数均小于0.6,这表明磁场能够抵抗引力坍缩,且在这些源中磁压超过内部湍流压力。在SMM2中,动能和引力能彼此相当,但均小于磁能。我们提出了马头星云整体磁场结构的示意图。SMM1中的磁力线似乎在光解离区形成过程中被压缩并重新排列,而可能埋藏更深的SMM2则可能继承了激波前分子云的磁场。磁场目前似乎在支撑这两个源方面发挥着重要作用。

英文摘要:

We present the first polarized dust emission measurements of the Horsehead Nebula, obtained using the POL-2 polarimeter on the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) camera on the James Clerk Maxwell Telescope (JCMT). The Horsehead Nebula contains two sub-millimeter sources, a photodissociation region (PDR; SMM1) and a starless core (SMM2). We see well-ordered magnetic fields in both sources. We estimated plane-of-sky magnetic field strengths of 56$\pm$9 and 129$\pm$21 $μ$G in SMM1 and SMM2, respectively, and obtained mass-to-flux ratios and Alfvén Mach numbers of less than 0.6, suggesting that the magnetic field can resist gravitational collapse and that magnetic pressure exceeds internal turbulent pressure in these sources. In SMM2, the kinetic and gravitational energies are comparable to one another, but less than the magnetic energy. We suggest a schematic view of the overall magnetic field structure in the Horsehead Nebula. Magnetic field lines in SMM1 appear have been compressed and reordered during the formation of the PDR, while the likely more-embedded SMM2 may have inherited its field from that of the pre-shock molecular cloud. The magnetic fields appear to currently play an important role in supporting both sources.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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