在W33综合体周围的扩展物理系统中发现不同的环境
Uncovering distinct environments in an extended physical system around the W33 complex
摘要：
我们提出了一个大规模的物理系统包含W33复杂的多波长调查。扩展系统（~50 pc x 37 pc）是根据分子气体在[29.6，60.2] km/s的分布和88个ATLASGAL 870微米尘埃团在d ~2.6 kpc的分布选择的。在13 CO和C18 O辐射图中追踪到的扩展系统/分子云包含了几个由OB星（年龄约0.3-1.0百万年）激发的HII区和一个热超临界暗条（“fs 1”，长度约17 pc）。没有电离气体的暗条显示尘埃温度（Td）为~19 K，而HII区的Td为~21-29 K。这表明云中存在两种不同的环境。I类年轻恒星天体（平均年龄约为440万年）的分布可以追溯到恒星形成的早期阶段（SF）。至少有三个速度分量（约35，45，和53公里/秒）的系统进行了调查。13 CO和C18 O的分析揭示了35和53 km/s附近云成分的空间和速度联系。观测到的位置，以前已知的来源，W33主，W33 A和O 4 -7I星，被发现对这两个云组件的互补分布。暗条“fs 1”和一个先前已知的物体W33 B被看到朝向云的重叠区域，在那里持续的SF活动是明显的。一个方案有关的收敛/碰撞流从两个不同的速度分量似乎很好地解释了观察到的路标SF活动的系统。
英文摘要：
We present a multi-wavelength investigation of a large-scale physical system containing the W33 complex. The extended system (~50 pc x 37 pc) is selected based on the distribution of molecular gas at [29.6, 60.2] km/s and of 88 ATLASGAL 870 micron dust clumps at d ~2.6 kpc. The extended system/molecular cloud traced in the maps of 13CO and C18O emission contains several HII regions excited by OB stars (age ~0.3-1.0 Myr) and a thermally supercritical filament ("fs1", length ~17 pc). The filament, devoid of the ionized gas, shows dust temperature (T_d) of ~19 K, while the HII regions are depicted with T_d of ~21-29 K. It suggests the existence of two distinct environments in the cloud. The distribution of Class I young stellar objects (mean age ~0.44 Myr) traces the early stage of star formation (SF) toward the cloud. At least three velocity components (around 35, 45, and 53 km/s) are investigated toward the system. The analysis of 13CO and C18O reveals the spatial and velocity connections of cloud components around 35 and 53 km/s. The observed positions of previously known sources, W33 Main, W33 A and O4-7I stars, are found toward a complementary distribution of these two cloud components. The filament "fs1" and a previously known object W33 B are seen toward the overlapping areas of the clouds, where ongoing SF activity is evident. A scenario concerning the converging/colliding flows from two different velocity components appears to explain well the observed signposts of SF activities in the system.
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