Possible Counterrotation between the Disk and Protostellar Envelope around the Class I Protostar IRAS 04169+2702
Possible Counterrotation between the Disk and Protostellar Envelope around the Class I Protostar IRAS 04169+2702
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DOI：
10.3847/1538-4357/aadb93
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
S. Takakuwa;Y. Tsukamoto;K. Saigo;M. Saito
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文献类型：
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作者：
S. Takakuwa;Y. Tsukamoto;K. Saigo;M. Saito
本文介绍了对I类原恒星IRAS 04169+2702的亚毫米波阵列（SMA）观测和数据分析的结果。高分辨率(~ 0。″5)13CO（3-2）图像立方体显示了一个紧凑的（r > 100 au）结构，具有西北（蓝色）到东南（红色）的速度梯度，以0.9 mm的尘埃连续辐射为中心。从SMA 12CO（2-1）数据中可以看出，速度梯度的方向与分子流出的轴线正交。在SO（65-54）管线中也可以看到类似的气体成分。另一方面，C18O（2-1）的发射显示出一个更大的（r ~ 400 au）分量，具有相反的速度梯度，西北（红色）到东南（蓝色）。对能见度数据的直接拟合也证实了不同分子线的速度梯度相反。我们已经建立了一个正向旋转和反向旋转的开普勒盘和一个原恒星包层的模型，包括SMA成像模拟。反向旋转模型能较好地再现观测到的速度通道图，但拟合结果不具有统计学意义。推导出的模型参数如下：开普勒半径为200 au，中心恒星质量为0.1 M⊙，包层旋转和下落速度分别为0.20和0.16 km s−1。对这些结果的一种可能的解释是磁场在原恒星周围的圆盘形成过程中的影响，即霍尔效应。
We present results from our Submillimeter Array (SMA) observations and data analyses of the SMA archival data of the Class I protostar IRAS 04169+2702. The high-resolution (∼0.″5) 13CO (3–2) image cube shows a compact (r ≲ 100 au) structure with a northwest (blue) to southeast (red) velocity gradient, centered on the 0.9 mm dust continuum emission. The direction of the velocity gradient is orthogonal to the axis of the molecular outflow as seen in the SMA 12CO (2–1) data. A similar gas component is seen in the SO (65–54) line. On the other hand, the C18O (2–1) emission traces a more extended (r ∼ 400 au) component with the opposite, northwest (red) to southeast (blue) velocity gradient. Such opposite velocity gradients in the different molecular lines are also confirmed from direct fitting to the visibility data. We have constructed models of a forward-rotating and counterrotating Keplerian disk and a protostellar envelope, including the SMA imaging simulations. The counterrotating model could better reproduce the observed velocity channel maps, although we could not obtain statistically significant fitting results. The derived model parameters are as follows: Keplerian radius of 200 au, central stellar mass of 0.1 M⊙, and envelope rotational and infalling velocities of 0.20 and 0.16 km s−1, respectively. One possible interpretation for these results is the effect of the magnetic field in the process of disk formation around protostars, i.e., the Hall effect.