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arXiv 2109.01231astro-ph.GAastro-ph.SR
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70 $μ$ m暗高质量团块早期阶段的ALMA调查(ASHES)。IV。G023 .477中的恒星形成特征

The ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477

Kaho Morii, Patricio Sanhueza, Fumitaka Nakamura, James M. Jackson, Shanghuo Li, Henrik Beuther, Qizhou Zhang, Siyi Feng, Daniel Tafoya, Andrés E. Guzmán, Natsu… 展开作者

Kaho Morii, Patricio Sanhueza, Fumitaka Nakamura, James M. Jackson, Shanghuo Li, Henrik Beuther, Qizhou Zhang, Siyi Feng, Daniel Tafoya, Andrés E. Guzmán, Natsuko Izumi, Takeshi Sakai, Xing Lu, Ken'ichi Tatematsu, Satoshi Ohashi, Andrea Silva, Fernando A. Olguin, Yanett Contreras

摘要:

质量为$\sim$ 1000 $M_\odot$,表面密度为$\sim$ 0.5 g cm $^{-2}$,G023.477+0.114也被称为IRDC 18310-4,是一个有可能形成高质量恒星的红外暗云,被认为是一个有希望的星前星团候选者。为了描述高质量恒星形成的早期阶段,我们观测了G023.477+0.114,这是ALMA对70 $μ$ m暗高质量团块早期阶段(ASHES)调查的一部分。我们已经进行了$\sim$ 1。“使用阿塔卡马大型毫米/亚毫米阵列(ALMA)在1.3毫米处对尘埃连续体和分子谱线发射进行2分辨率观测。我们确定了11个核心,其质量范围从1.1 $M_\odot$到19.0 $M_\odot$。忽略磁场,核心的维里参数低于1,这意味着核心是引力约束的。然而,当磁场包括在内时,星前核接近维里平衡,而原恒星核保持亚维里化。恒星形成活动已经在这一丛开始。在CO和SiO中检测到四个准直流出。H $_2$ CO和CH $_3$ OH发射与CO和SiO发射中看到的高速分量一致。流出物对于出生丝和磁场是随机定向的。位置-速度图表明,即使在原恒星形成的非常早期阶段,阶段性的物质抛射也已经开始。这些核心的质量与IRDC可能形成的最大恒星质量(8-19 $M_\odot$)相当。我们探讨了IRDC G023.477+0.114如何在理论情景中最终形成大质量恒星的两种可能性。

英文摘要:

With a mass of $\sim$1000 $M_\odot$ and a surface density of $\sim$0.5 g cm$^{-2}$, G023.477+0.114 also known as IRDC 18310-4 is an infrared dark cloud (IRDC) that has the potential to form high-mass stars and has been recognized as a promising prestellar clump candidate. To characterize the early stages of high-mass star formation, we have observed G023.477+0.114 as part of the ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES). We have conducted $\sim$1."2 resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 mm in dust continuum and molecular line emission. We identified 11 cores, whose masses range from 1.1 $M_\odot$ to 19.0 $M_\odot$. Ignoring magnetic fields, the virial parameters of the cores are below unity, implying that the cores are gravitationally bound. However, when magnetic fields are included, the prestellar cores are close to virial equilibrium, while the protostellar cores remain sub-virialized. Star formation activity has already started in this clump. Four collimated outflows are detected in CO and SiO. H$_2$CO and CH$_3$OH emission coincide with the high-velocity components seen in the CO and SiO emission. The outflows are randomly oriented for the natal filament and the magnetic field. The position-velocity diagrams suggest that episodic mass ejection has already begun even in this very early phase of protostellar formation. The masses of the identified cores are comparable to the expected maximum stellar mass that this IRDC could form (8-19 $M_\odot$). We explore two possibilities on how IRDC G023.477+0.114 could eventually form high-mass stars in the context of theoretical scenarios.

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