论文标题
宽角度的原始恒星流出由狭窄的喷气机驱动的分层芯
Wide-angle protostellar outflows driven by narrow jets in stratified cores
论文作者
论文摘要
大多数对恒星形成的流出反馈的模拟都是基于以下假设：流出是由广角“ X-Wind”驱动的，而不是狭窄的射流。但是，最初针对纯喷气驱动流的论点是基于在均匀介质中稳定的弹出，这一概念不再基于最近的观察结果支持。我们旨在确定在密度分层的，自给自足的核心中发射的脉冲窄射流是否可以在无广角风组件的帮助下繁殖典型的分子流出特性。我们使用MPI-AMRVAC代码进行了轴对称流体动力学模拟，并在最高10000年的时间尺度上具有光学较薄的辐射冷却。然后，我们计算并比较了预测属性与观察数据。首先，与通过均匀的芯相比，喷射驱动的壳通过芯的密度急剧降低的芯延伸更快，更宽。其次，当吹入相同的奇异扁平核心时，喷气驱动的壳具有与大角度风向的外壳相似的宽度，但在长时间的长时间尺度上的扩展下降。该流程采用锥形形状，基本开头的角度达到$ 90 \ unicode {xb0} $。第三，在$ \ sim $ 10000年之后，脉冲喷气驱动的外壳显示出合适的功能和定性的相似之处，最近观察到ProtoStellar流出与Atacama大毫米阵列（ALMA），例如HH46-47和Carma-7。特别是，在壳宽度，开头角度，位置图表和质量分布中可以看到相似性，其中一些显示出比基于广角“ X-Wind”模型的模拟中的相似之处。因此，除了千年整合时间外，现实的环境密度分层对于可靠地预测脉冲喷射驱动的流出的特性并与观测值对抗同样至关重要。
Most simulations of outflow feedback on star formation are based on the assumption that outflows are driven by a wide angle "X-wind," rather than a narrow jet. However, the arguments initially raised against pure jet-driven flows were based on steady ejection in a uniform medium, a notion that is no longer supported based on recent observations. We aim to determine whether a pulsed narrow jet launched in a density-stratified, self-gravitating core could reproduce typical molecular outflow properties, without the help of a wide-angle wind component. We performed axisymmetric hydrodynamic simulations using the MPI-AMRVAC code with optically thin radiative cooling on timescales up to 10000 yrs. Then we computed and compared the predicted properties with observational data. First, the jet-driven shell expands faster and wider through a core with steeply decreasing density than through an uniform core. Second, when blown into the same singular flattened core, a jet-driven shell has a similar width as a wide-angle wind-driven shell in the first few hundred years, but a decelerating expansion on long timescales. The flow adopts a conical shape and a base opening angle reaching up to $90\unicode{xb0}$. Third, after $\sim$ 10000 yrs, a pulsed jet-driven shell shows fitting features and a qualitative resemblance with recent observations of protostellar outflows with the Atacama Large Millimeter Array (ALMA), such as HH46-47 and CARMA-7. In particular, similarities are seen in the shell widths, opening angles, position-velocity diagrams, and mass-velocity distribution, with some showing a closer resemblance than in simulations based on a wide-angle "X-wind" model. Therefore, a realistic ambient density stratification in addition to millenia-long integration times are equally essential to reliably predict the properties of outflows driven by a pulsed jet and to confront them with the observations.
