论文标题
Musca细丝的形成：由于云云碰撞而导致积聚流中不对称的证据
Formation of the Musca filament: Evidence for asymmetries in the accretion flow due to a cloud-cloud collision
论文作者
论文摘要
语境。在星际培养基中，密集的分子丝无处不在，但它们的内部物理条件和形成机制仍在争论中。目标。我们研究了穆斯卡丝和Chamaeleon-Musca综合体中的运动学和物理条件，以限制细丝形成的物理。方法。我们用切开Musca细丝的顶点望远镜制作了CO（2-1）同位素图。我们进一步研究了Musca Cloud的Nanten2 $^{12} $ CO（1-0）图和Chamaeleon-Musca综合体的HI排放。结果。 Musca云包含多个速度成分。 CO排放的辐射转移建模表明Musca丝由感冒（$ \ sim $ 10 K），致密（N $ _ {h_2} \ sim $ 10 $ 10 $^4 $ cm $^{ - 3} $），最好用Cylindrical deemetry进行描述。连接到Crest，一个单独的气体组件，t $ \ sim $ 15 k，n $ _ {h_2} \ sim $ 10 $^3 $ cm $^{ - 3} $，所谓的链。灯丝波峰具有横向速度梯度，与附近环境云的运动学相关。在研究大型运动学时，我们发现了从50 pc hi云到穆斯卡细丝的不对称运动学的连贯性。我们还报告了一个强烈的[C $^{18} $ O]/[$^{13} $ co]的丰度下降的顺序从细丝冠上降到了一条距离的股票，$ <$ <$ 0.2 $ <$ <$ 0.2 pc，在一个弱的远欧traviolet（fuv）字段中。结论。密集的穆斯卡丝冠是一个长期的（几个穿越时间），动态结构，由于持续的质量积聚，可以在不久的将来形成恒星。这种质量积聚似乎是由高云云碰撞触发的，该碰撞弯曲了密集的细丝周围的磁场。然后，磁场的这种弯曲是造成观察到的穆斯卡细丝的不对称积聚场景的原因，例如，在位置速度（PV）图中被视为V形。
Context. Dense molecular filaments are ubiquituous in the interstellar medium, yet their internal physical conditions and formation mechanism remain debated. Aims. We study the kinematics and physical conditions in the Musca filament and the Chamaeleon-Musca complex to constrain the physics of filament formation. Methods. We produced CO(2-1) isotopologue maps with the APEX telescope that cut through the Musca filament. We further study a NANTEN2 $^{12}$CO(1-0) map of the Musca cloud and the HI emission of the Chamaeleon-Musca complex. Results. The Musca cloud contains multiple velocity components. Radiative transfer modelling of the CO emission indicates that the Musca filament consists of a cold ($\sim$10 K), dense (n$_{H_2}\sim$10$^4$ cm$^{-3}$) crest, which is best described with a cylindrical geometry. Connected to the crest, a separate gas component at T$\sim$15 K and n$_{H_2}\sim$10$^3$ cm$^{-3}$ is found, the so-called strands. The filament crest has a transverse velocity gradient that is linked to the kinematics of the nearby ambient cloud. Studying the large scale kinematics, we find coherence of the asymmetric kinematics from the 50 pc HI cloud down to the Musca filament. We also report a strong [C$^{18}$O]/[$^{13}$CO] abundance drop by an order of magnitude from the filament crest to the strands over a distance $<$ 0.2 pc in a weak far-ultraviolet (FUV) field. Conclusions. The dense Musca filament crest is a long-lived (several crossing times), dynamic structure that can form stars in the near future because of continuous mass accretion. This mass accretion appears to be triggered by a HI cloud-cloud collision, which bends the magnetic field around dense filaments. This bending of the magnetic field is then responsible for the observed asymmetric accretion scenario of the Musca filament, which is, for instance, seen as a V-shape in the position-velocity (PV) diagram.
