用Parkes NH $_3$观测研究南部大质量恒星形成区的物理特征
Physical characterisation of southern massive star-forming regions using Parkes NH$_3$ observations
摘要：
我们已经进行了Parkes氨谱线研究，在最低的两个反转过渡，南部的大质量恒星形成区域，包括年轻的大质量候选原恒星，其目的是表征大质量恒星形成的最早阶段。来自Hill等人的亚毫米连续辐射研究的138个源，发现具有鲁棒的（1，1）检测，包括具有两个速度分量的两个源，并且在（2，2）过渡中有102个。我们确定氨线属性的来源：线宽，通量密度，动力学温度，NH $_3$柱密度和不透明度，并重新审视我们的SED建模程序，以获得52个来源的质量。通过将连续排放信息与氨观测相结合，我们基本上限制了大质量团块的物理性质。氨和连续观测之间有明显的互补性，用于推导物理参数。在Hill等人的连续体研究中确定的仅MM类，显示较小的尺寸，质量和速度分散和/或湍流比恒星形成的团块，这表明一个静止的星前阶段和/或形成质量较小的恒星。
英文摘要：
We have undertaken a Parkes ammonia spectral line study, in the lowest two inversion transitions, of southern massive star formation regions, including young massive candidate protostars, with the aim of characterising the earliest stages of massive star formation. 138 sources from the submillimetre continuum emission studies of Hill et al., were found to have robust (1,1) detections, including two sources with two velocity components, and 102 in the (2,2) transition. We determine the ammonia line properties of the sources: linewidth, flux density, kinetic temperature, NH$_3$ column density and opacity, and revisit our SED modelling procedure to derive the mass for 52 of the sources. By combining the continuum emission information with ammonia observations we substantially constrain the physical properties of the high-mass clumps. There is clear complementarity between ammonia and continuum observations for derivations of physical parameters. The MM-only class, identified in the continuum studies of Hill et al., display smaller sizes, mass and velocity dispersion and/or turbulence than star-forming clumps, suggesting a quiescent prestellar stage and/or the formation of less massive stars.
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