The contribution of the magnetic field to the formation of high-mass stars is poorly understood. We report the high angular resolution (∼0.″3, 870 au) map of the magnetic field projected on the plane of the sky (B _POS) toward the high-mass star-forming region G333.46−0.16 (G333), obtained with the Atacama Large Millimeter/submillimeter Array at 1.2 mm as part of the Magnetic fields in Massive star-forming Regions survey. The B _POS morphology found in this region is consistent with a canonical “hourglass” with an embedded flattened envelope in a perpendicular direction, which suggests a dynamically important field. This region is fragmented into two protostars that appear to be gravitationally bound in a stable binary system with a separation of ∼1740 au. Interestingly, by analyzing H¹³CO⁺ (J = 3–2) line emission, we find no velocity gradient over the extent of the continuum, which is consistent with a strong field. We model the B _POS, obtaining a marginally supercritical mass-to-flux ratio of 1.43, suggesting an initially strongly magnetized environment. Based on the Davis–Chandrasekhar–Fermi method, the magnetic field strength toward G333 is estimated to be 5.7 mG. The absence of strong rotation and outflows toward the central region of G333 suggests strong magnetic braking, consistent with a highly magnetized environment. Our study shows that despite being a strong regulator, the magnetic energy fails to prevent the process of fragmentation, as revealed by the formation of the two protostars in the central region.

中文翻译：

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大质量恒星形成区域 (MagMaR) 中的磁场：使用 ALMA 揭示 G333.46–0.16 中的沙漏磁场


人们对磁场对大质量恒星形成的贡献知之甚少。我们报告了投影在天空平面 (B _POS ) 上朝向大质量恒星形成区域 G333.46−0.16 (G333) 的磁场的高角分辨率 (∼0.″3, 870 au) 地图，作为大质量恒星形成区域磁场调查的一部分，使用 1.2 毫米处的阿塔卡马大型毫米/亚毫米阵列获得。在该区域发现的 B _POS形态与典型的“沙漏”一致，在垂直方向上嵌入扁平包络，这表明这是一个动态重要的场。该区域分裂成两颗原恒星，它们似乎被引力束缚在一个稳定的双星系统中，距离约为 1740 个天文单位。有趣的是，通过分析 H ¹³ CO ⁺ (J = 3–2) 线发射，我们发现在连续体范围内没有速度梯度，这与强场一致。我们对 B _POS进行建模，获得了 1.43 的超临界质量通量比，表明最初存在强磁化环境。根据 Davis-Chandrasekhar-Fermi 方法，G333 的磁场强度估计为 5.7 mG。 G333 中心区域没有强烈的旋转和流出表明存在强烈的磁制动，这与高度磁化的环境一致。我们的研究表明，尽管磁能是一个强大的调节器，但它无法阻止分裂过程，正如中心区域两颗原恒星的形成所揭示的那样。