标题： 原始褐矮星的复杂结构 显示英文标题

标题： Complex structure of a proto-brown dwarf

摘要： 我们展示了针对一颗非常年轻的原棕矮星系统ISO-OPH 200的ALMA $^{12}$CO (2-1)，$^{13}$CO (2-1)，C$^{18}$O (2-1)分子线观测结果。 我们利用棕矮星形成的核心坍缩模拟，对该系统的复杂内部结构进行了物理+化学建模。 在6000年（$\sim$）岁时的模型能够很好地拟合观测到的动力学和光谱，并重现了在矩量图中看到的复杂结构。 建模结果表明，$^{12}$CO 排放追踪一个延伸的（$\sim$1000 au）分子外流和一个明亮的冲击节，$^{13}$CO 追踪外部（$\sim$1000 au）包层/伪盘，而 C$^{18}$O 追踪内部（$\sim$500 au）伪盘。 在873$\mu$米图像中测量到的$\sim$的源大小为8.6天文单位，与模型预测的内禀开普勒盘大小相当。 ISO-OPH 200的三维模型结构表明，这个系统部分通过一个宽广的外流空腔观测，导致了对外流的直接观测以及对包层/伪盘的部分观测。 我们已经论证，由于其不寻常的方向，ISO-OPH 200被误分类为平坦盘（Class Flat）天体。 该系统的各种特征，尤其是年轻的流出动力学年龄（$\sim$616 年）和高流出速率（$\sim$1$\times$10$^{-7}$ M$_{\odot}$ 年$^{-1}$），以及在 10$\mu$米中红外光谱中的硅酸盐吸收，在包层/盘中的原始ISM型尘埃，扩展包层和流出的相当大小，表明ISO-OPH 200 是一个早期的 0 类阶段系统，通过非常低质量核心的引力塌缩以类似于恒星的机制形成。 显示英文摘要

摘要： We present ALMA $^{12}$CO (2-1), $^{13}$CO (2-1), C$^{18}$O (2-1) molecular line observations of a very young proto-brown dwarf system, ISO-OPH 200. We have conducted physical+chemical modelling of the complex internal structure for this system using the core collapse simulations for brown dwarf formation. The model at an age of $\sim$6000 yr can provide a good fit to the observed kinematics, spectra, and reproduce the complex structures seen in the moment maps. Results from modelling indicate that $^{12}$CO emission is tracing an extended ($\sim$1000 au) molecular outflow and a bright shock knot, $^{13}$CO is tracing the outer ($\sim$1000 au) envelope/pseudo-disc, and C$^{18}$O is tracing the inner ($\sim$500 au) pseudo-disc. The source size of $\sim$8.6 au measured in the 873$\mu$m image is comparable to the inner Keplerian disc size predicted by the model. A 3D model structure of ISO-OPH 200 suggests that this system is viewed partially through a wide outflow cavity resulting in a direct view of the outflow and a partial view of the envelope/pseudo-disc. We have argued that ISO-OPH 200 has been mis-classified as a Class Flat object due to the unusual orientation. The various signatures of this system, notably, the young $\sim$616 yr outflow dynamical age and high outflow rate ($\sim$1$\times$10$^{-7}$ M$_{\odot}$ yr$^{-1}$), silicate absorption in the 10$\mu$m mid-infrared spectrum, pristine ISM-like dust in the envelope/disc, comparable sizes of the extended envelope and outflow, indicate that ISO-OPH 200 is an early Class 0 stage system formed in a star-like mechanism via gravitational collapse of a very low-mass core.