标题： 奥里昂A云中与无恒星核心相关联的湍流气体组分的检测 显示英文标题

标题： Detection of a turbulent gas component associated with a starless core with subthermal turbulence in the Orion A cloud

摘要： 我们报告在猎户座A云中无恒星核心TUKH122的NH$_3$发射中检测到一个翼成分，该核心具有亚热湍流。 这个NH$_3$核被认为正处于恒星形成的边缘，因为NH$_3$核内部的湍流几乎完全消散，并且它被CCS包围，这类似于金牛座中显示出吸积运动的预恒星核心L1544。 观测使用了野边山45米望远镜，在0.05 km s$^{-1}$的速度分辨率下进行。 我们发现NH$_3$线轮廓由两个成分组成。 静止的主要成分具有0.3 km s$^{-1}$的小线宽，主要由热运动主导，而红移翼成分具有1.36 km s$^{-1}$的大线宽，代表湍流运动。 这些组件显示的动能温度分别为11 K和$<$30 K。此外，NH$_3$静止气体（$VLSR=3.7$km s$^{-1}$）和湍流气体（$VLSR=4.4$km s$^{-1}$）之间有明显的速度偏移。 湍流气体的质心速度对应于由$^{13}$CO ($J=1-0$) 和 CS ($J=2-1$) 线所追踪的周围气体的速度。 LVG模型计算显示，CS和CO的湍流气体温度为$8-13$ K，H$_2$密度约为$10^4$ cm$^{-3}$，表明湍流组分的温度也约为10 K。NH$_3$静止和翼成分的检测可能表明湍流母云到静止致密核心的急剧过渡。 显示英文摘要

摘要： We report the detection of a wing component in NH$_3$ emission toward the starless core TUKH122 with subthermal turbulence in the Orion A cloud. This NH$_3$ core is suggested to be on the verge of star formation because the turbulence inside the NH$_3$ core is almost completely dissipated, and also because it is surrounded by CCS, which resembles the prestellar core L1544 in Taurus showing infall motions. Observations were carried out with the Nobeyama 45 m telescope at 0.05 km s$^{-1}$ velocity resolution. We find that the NH$_3$ line profile consists of two components. The quiescent main component has a small linewidth of 0.3 km s$^{-1}$ dominated by thermal motions, and the red-shifted wing component has a large linewidth of 1.36 km s$^{-1}$ representing turbulent motions. These components show kinetic temperatures of 11 K and $<$ 30 K, respectively. Furthermore, there is a clear velocity offset between the NH$_3$ quiescent gas ($VLSR=3.7$ km s$^{-1}$) and the turbulent gas ($VLSR=4.4$ km s$^{-1}$). The centroid velocity of the turbulent gas corresponds to that of the surrounding gas traced by the $^{13}$CO ($J=1-0$) and CS ($J=2-1$) lines. LVG model calculations for CS and CO show that the turbulent gas has a temperature of $8-13$ K and an H$_2$ density of ~ $10^4$ cm$^{-3}$, suggesting that the temperature of the turbulent component is also ~ 10 K. The detections of both NH$_3$ quiescent and wing components may indicate a sharp transition from the turbulent parent cloud to the quiescent dense core.