SOFIA and ALMA Investigate Magnetic Fields and Gas Structures in Massive Star Formation: The Case of the Masquerading Monster in BYF 73
SOFIA and ALMA Investigate Magnetic Fields and Gas Structures in Massive Star Formation: The Case of the Masquerading Monster in BYF 73
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DOI：
10.3847/1538-4357/acac27
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发表时间：
2023-01
期刊：
影响因子：
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通讯作者：
P. Barnes;S. Ryder;G. Novak;R. Crutcher;L. Fissel;R. Pitts;William J. Schap III
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文献类型：
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作者：
P. Barnes;S. Ryder;G. Novak;R. Crutcher;L. Fissel;R. Pitts;William J. Schap III
我们介绍了红外天文学平流层天文台(SOFIA)+阿塔卡马大毫米/亚毫米阵列(ALMA)的连续谱和谱线偏振数据，揭示了这个不同寻常的大质量恒星形成实验室中的磁场形态、气体结构和能量学的重要细节。μmHAWC+偏振图发现，在云层最密集的内部0.55×0.40pC部分，磁场高度有序，而云层外层的形态并不明显。3 mm连续的ALMA极化数据揭示了内区的几种结构，包括围绕中心大质量原恒星对象MIR2的一个∼500M⊙“流光”，其磁场大部分平行于东西方向，但沿MIR2南北方向。在阈值NCrit=6.6×1026m−2，nCrit=2.5×1011m−3，BCrit=42±7nT时，磁场方向从基本平行于列密度结构变为主要垂直。ALMA还绘制了云中12co的Goldreich-Kylafis极化图，在总强度和极化通量方面都追踪到了从MIR 2流出的与Streamer强烈相互作用的强大双极外流。磁场也强烈地沿着流出方向排列；从能量上讲，它可能主导着和平号2附近的流出，这包含了罕见的证据，表明这种流出来自磁心离心源。流光的一部分可能是围绕MIR 2的开普勒式旋转，这意味着原恒星+盘+包层的引力质量为1350±50M⊙；或者，这些运动学可以用朝向950±35M⊙天体的自由落体气体来解释。对MIR-2的高吸积率显然是通过流光/盘发生的，并且可以通过引力能量释放来解释MIR-2‘S总光度的∼33%。
We present Stratospheric Observatory For Infrared Astronomy (SOFIA) + Atacama Large Millimeter/submillimeter Array (ALMA) continuum and spectral-line polarization data on the massive molecular cloud BYF 73, revealing important details about the magnetic field morphology, gas structures, and energetics in this unusual massive star formation laboratory. The 154 μm HAWC+ polarization map finds a highly organized magnetic field in the densest, inner 0.55 × 0.40 pc portion of the cloud, compared to an unremarkable morphology in the cloud’s outer layers. The 3 mm continuum ALMA polarization data reveal several more structures in the inner domain, including a parsec-long, ∼500 M ⊙ “Streamer” around the central massive protostellar object MIR 2, with magnetic fields mostly parallel to the east–west Streamer but oriented north–south across MIR 2. The magnetic field orientation changes from mostly parallel to the column density structures to mostly perpendicular, at thresholds N crit = 6.6 × 1026 m−2, n crit = 2.5 × 1011 m−3, and B crit = 42 ± 7 nT. ALMA also mapped Goldreich–Kylafis polarization in 12CO across the cloud, which traces, in both total intensity and polarized flux, a powerful bipolar outflow from MIR 2 that interacts strongly with the Streamer. The magnetic field is also strongly aligned along the outflow direction; energetically, it may dominate the outflow near MIR 2, comprising rare evidence for a magnetocentrifugal origin to such outflows. A portion of the Streamer may be in Keplerian rotation around MIR 2, implying a gravitating mass 1350 ± 50 M ⊙ for the protostar+disk+envelope; alternatively, these kinematics can be explained by gas in free-fall toward a 950 ± 35 M ⊙ object. The high accretion rate onto MIR 2 apparently occurs through the Streamer/disk, and could account for ∼33% of MIR 2's total luminosity via gravitational energy release.