COLLIDING FILAMENTS AND A MASSIVE DENSE CORE IN THE CYGNUS OB 7 MOLECULAR CLOUD
COLLIDING FILAMENTS AND A MASSIVE DENSE CORE IN THE CYGNUS OB 7 MOLECULAR CLOUD
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DOI：
10.1088/0004-637x/797/1/58
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发表时间：
2014-11
期刊：
影响因子：
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通讯作者：
K. Dobashi;Tomoaki Matsumoto;T. Shimoikura;H. Saito;K. Akisato;K. Ohashi;Keisuke Nakagomi
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文献类型：
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作者：
K. Dobashi;Tomoaki Matsumoto;T. Shimoikura;H. Saito;K. Akisato;K. Ohashi;Keisuke Nakagomi
我们报告的结果进行了分子线观测对一个巨大的致密核心的天鹅座OB 7分子云。它的核心有着非常大的质量（1.1 × 104 M）和尺寸（1.2 × 5 pc 2），但没有大质量的年轻星星形成。我们使用野边山射电天文台的45米望远镜在各种分子谱线（如C18 O（J = 1-0））中观察到这个核心。我们发现，核心有一个细长的形态组成的几个长丝和核心状结构。这些暗条质量很大（102-103 M），它们显然在相互碰撞。一些年轻恒星天体的候选者分布在它们的交叉点周围，这表明细丝的碰撞可能影响了它们的形成。为了理解这种碰撞细丝的形成和演化，我们使用自适应网格细化技术进行了数值模拟，采用观测到的核心参数（质量和大小）作为初始条件。结果表明，细丝的形成与文献中其他早期的小核心模拟一样，但我们不能简单地通过假设大的初始质量和尺寸来再现细丝的碰撞。我们发现，只有当初始核中存在大的速度梯度时，才会发生细丝的碰撞，在某种意义上压缩它。我们认为，观察到的核实际上是由外部效应压缩的，例如，来自附近超新星遗迹的冲击，包括HB 21，它被认为与天鹅座OB 7分子云相互作用。
We report the results of molecular line observations carried out toward a massive dense core in the Cyg OB 7 molecular cloud. The core has an extraordinarily large mass (∼1.1 × 104 M☉) and size (∼2 × 5 pc2), but there is no massive young star forming therein. We observed this core in various molecular lines such as C18O(J = 1–0) using the 45 m telescope at Nobeyama Radio Observatory. We find that the core has an elongated morphology consisting of several filaments and core-like structures. The filaments are massive (102–103 M☉), and they are apparently colliding with one another. Some candidates for young stellar objects are distributed around their intersection, suggesting that the collisions of the filaments may have influenced their formation. To understand the formation and evolution of such colliding filaments, we performed numerical simulations using the adaptive mesh refinement technique, adopting the observed core parameters (the mass and size) as the initial conditions. The results indicate that the filaments are formed as seen in other earlier simulations for small cores in the literature, but we could not reproduce the collisions of the filaments simply by assuming a large initial mass and size. We find that collisions of the filaments occur only when there is a large velocity gradient in the initial core, in a sense compressing it. We suggest that the observed core was actually compressed by an external effect, e.g., shocks from nearby supernova remnants, including HB 21 which has been suggested to be interacting with the Cyg OB 7 molecular cloud.