arXiv 2209.096092022-09-20astro-ph.GA

Sh2-112丝状云复合体中恒星和团簇形成

Star and Cluster Formation in the Sh2-112 Filamentary Cloud Complex

Alik Panja, Yan Sun, Wen Ping Chen, Soumen Mondal

备注：: 29 pages, 16 figures, 5 tables, accepted for publication in ApJ
DOI：: 10.3847/1538-4357/ac940f

摘要：

我们介绍了发射星云Sh 2 -112周围的恒星形成活动。在距离$\sim2.1$ ~kpc处，这个\ion{H}{2}复合体，本身半径为3~pc，被大质量恒星（O 8\，V）BD $+$ 45\，3216照亮。伴随的分子云以$2\fdg0\times0\fdg83$的角尺度沿银河经度延伸，相当于73 pc乘30 pc的线性大小。高分辨率（$30\arcsec$）的消光图显示了一条与类金刚石结构对齐的尘埃团链，平均消光为$A_{V} \sim 2.78$ ~mag，最大消光为$\sim17$ ~ mag。我们的分析导致了对丰富种群的识别（$\sim 500$）的年轻人（$\sim 1$ ~Myr的平均年龄）恒星，加上大量（$\sim 350$）H $α$发射体，在空间上与对流云相关。位于云边缘附近的发光恒星BD $+$ 45\，3216在电离辐射遇到致密气体时产生了弧形图案，形成了水泡状形态。我们发现了三个不同的年轻恒星群，它们都与星云复合体中相对密集的部分重合，这表明恒星正在形成。此外，由CO同位素示踪的云丝（激发温度$\sim$ ~K）几乎延伸到$\sim 80$ ~pc，除了在致密的核心（激发温度$\sim$ 28- 32 ~K），没有电离气体，其中有大量的由OB星（动力学年龄$\sim$ 0.18- 1.0 ~Myr）激发的电离辐射。主暗条的径向速度是动态的（中值$\sim -3.65$ ~km~s $^{-1}$），从银河系东向西逐渐增大，具有质量流的特征，在中心枢纽形成大质量恒星/星团。

英文摘要：

We present the star formation activity around the emission nebula Sh2-112. At a distance of $\sim2.1$~kpc, this \ion{H}{2} complex, itself 3~pc in radius, is illuminated by the massive star (O8\,V) BD$+$45\,3216. The associated molecular cloud extends in angular scales of $2\fdg0\times0\fdg83$, corresponding to linear sizes of 73~pc by 30~pc, along the Galactic longitude. The high-resolution ($30\arcsec$) extinction map reveals a chain of dust clumps aligned with the filament-like structure with an average extinction of $A_{V} \sim 2.78$~mag, varying up to a maximum of $\sim17$~mag. Our analysis led to identification of a rich population ($\sim 500$) of young (average age of $\sim 1$~Myr) stars, plus a numerous number ($\sim 350$) of H$α$ emitters, spatially correlated with the filamentary clouds. Located near the edge of the cloud, the luminous star BD$+$45\,3216 has created an arc-like pattern as the ionizing radiation encounters the dense gas, forming a blister-shaped morphology. We found three distinct young stellar groups, all coincident with relatively dense parts of the cloud complex, signifying ongoing star formation. Moreover, the cloud filament (excitation temperature $\sim 10$~K) traced by the CO isotopologues and extending nearly $\sim 80$~pc is devoid of ionized gas except at the dense cores (excitation temperature $\sim$ 28--32~K) wherein significant ionized emission excited by OB stars (dynamical age $\sim$ 0.18--1.0~Myr) pertains. The radial velocity is dynamic (median $\sim -3.65$~km~s$^{-1}$) along the main filament, increasing from Galactic east to west, features mass flow to form the massive stars/clusters at the central hubs.

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