Spiral Arms, Infall, and Misalignment of the Circumbinary Disk from the Circumstellar Disks in the Protostellar Binary System L1551 NE
Spiral Arms, Infall, and Misalignment of the Circumbinary Disk from the Circumstellar Disks in the Protostellar Binary System L1551 NE
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DOI：
10.3847/1538-4357/aa6116
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发表时间：
2017-02
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影响因子：
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通讯作者：
S. Takakuwa;K. Saigo;Tomoaki Matsumoto;M. Saito;Jeremy Lim;T. Hanawa;Hsi-Wei Yen;P. Ho
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文献类型：
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作者：
S. Takakuwa;K. Saigo;Tomoaki Matsumoto;M. Saito;Jeremy Lim;T. Hanawa;Hsi-Wei Yen;P. Ho
本文报道了在阿尔马周期2对L1551 NE的0.9 mm连续谱的观测结果，C18 O（3-2），13 CO（3-2），SO（78-67）和CS（7-6）的发射。在0.“18（=25 Au）分辨率下，比我们的第0周观测高1.44倍，在0.9 mm发射中看到的环双星盘（CBD）显示为由一个北方和一个南方螺旋臂组成，南臂连接到源B周围的环星盘（CSD）。旋臂的西部比东部亮，表明存在m = 1的螺旋模式。在C18 O辐射中，确定了臂间区域的入流气体运动和臂中的外向气体运动。这些观察到的功能很好地再现与我们的数值模拟，从二进制系统的引力矩赋予角动量的螺旋臂区域和提取角动量的臂间区域。CBD的化学分化见于四种分子物种中。我们的第2周观测也分辨出了单个原恒星周围的CSD，束流解卷积的大小为0.″29 × 0.″19（=40 × 26 Au）（P.A. = 144°）和0.“26 × 0.”20（=36 × 27 Au）（P.A. = 147°）。这些CSD的位置和倾斜角度与CBD的位置和倾斜角度不一致。C18 O的发射跟踪了围绕源A的未对准盘的开普勒旋转。
We report the ALMA Cycle 2 observations of the Class I binary protostellar system L1551 NE in the 0.9 mm continuum, C18O (3–2), 13CO (3–2), SO (78–67), and CS (7–6) emission. At 0.″18 (=25 au) resolution, ∼4 times higher than that of our Cycle 0 observations, the circumbinary disk (CBD) as seen in the 0.9 mm emission is shown to be composed of a northern and a southern spiral arm, with the southern arm connecting to the circumstellar disk (CSD) around Source B. The western parts of the spiral arms are brighter than the eastern parts, suggesting the presence of an m = 1 spiral mode. In the C18O emission, the infall gas motions in the interarm regions and the outward gas motions in the arms are identified. These observed features are well reproduced with our numerical simulations, where gravitational torques from the binary system impart angular momenta to the spiral-arm regions and extract angular momenta from the interarm regions. Chemical differentiation of the CBD is seen in the four molecular species. Our Cycle 2 observations have also resolved the CSDs around the individual protostars, and the beam-deconvolved sizes are 0.″29 × 0.″19 (=40 × 26 au) (P.A. = 144°) and 0.″26 × 0.″20 (=36 × 27 au) (P.A. = 147°) for Sources A and B, respectively. The position and inclination angles of these CSDs are misaligned with those of the CBD. The C18O emission traces the Keplerian rotation of the misaligned disk around Source A.