Crescent-shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA
Crescent-shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA
复制标题
DOI：
10.3847/1538-4357/acb930
复制
发表时间：
2023-02
期刊：
影响因子：
--
通讯作者：
Naoto Harada;K. Tokuda;Hayao Yamasaki;Asako Sato;Mitsuki Omura;S. Hirano;T. Onishi;K. Tachihara;M. Machida
中科院分区：
文献类型：
--
作者：
Naoto Harada;K. Tokuda;Hayao Yamasaki;Asako Sato;Mitsuki Omura;S. Hirano;T. Onishi;K. Tachihara;M. Machida
我们报告的阿塔卡马大型毫米/亚毫米阵列研究的I类或II类中等质量的原恒星DK车在Chamaeleon II区域。12 CO（J = 2-1）图像的角分辨率为1″（250 Au），显示高速蓝移（70 km s-1）和红移（50 km s-1）发射，其中具有3000个Au尺度的新月形结构围绕1.3 mm连续统中追踪的原恒星盘。由于CO排放的高速分量与原恒星有关，我们得出结论，排放跟踪极上流出。蓝移出流叶具有明显的分层速度梯度，其中较高速度的分量位于新月形的内侧，这可以通过内半径中具有较高速度的出流模型来解释。基于直接驱动外流的情况下，我们估计的驱动半径从观察到的外流速度，发现驱动区域延伸超过2个数量级。的13 CO排放跟踪一个复杂的信封结构与弧形子结构的长度为1000 Au。我们将弧形结构确定为飘带，因为它们似乎与旋转的下落包络相连。DK Cha有助于了解年轻原恒星系统的近面对面配置所能看到的特征，为研究星星形成过程提供了另一种视角。
We report on an Atacama Large Millimeter/submillimeter Array study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The 12CO(J = 2–1) images have an angular resolution of ∼1″ (∼250 au) and show high-velocity blueshifted (≳70 km s−1) and redshifted (≳50 km s−1) emissions, which have 3000 au scale crescent-shaped structures around the protostellar disk traced in the 1.3 mm continuum. Because the high-velocity components of the CO emission are associated with the protostar, we concluded that the emission traces the pole-on outflow. The blueshifted outflow lobe has a clear layered velocity gradient with a higher-velocity component located on the inner side of the crescent shape, which can be explained by a model of an outflow with a higher velocity in the inner radii. Based on the directly driven outflow scenario, we estimated the driving radii from the observed outflow velocities and found that the driving region extends over 2 orders of magnitude. The 13CO emission traces a complex envelope structure with arc-like substructures with lengths of ∼1000 au. We identified the arc-like structures as streamers because they appear to be connected to a rotating infalling envelope. DK Cha is useful for understanding characteristics that are visible by looking at nearly face-on configurations of young protostellar systems, providing an alternative perspective for studying the star formation process.