The initial conditions for young massive cluster formation in the Galactic Centre: convergence of large-scale gas flows
The initial conditions for young massive cluster formation in the Galactic Centre: convergence of large-scale gas flows
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银河系中心年轻大质量星团形成的初始条件：大规模气流的汇聚
DOI：
10.1093/mnras/stac1378
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发表时间：
2022
影响因子：
4.8
通讯作者：
Ho, Luis C.
中科院分区：
文献类型：
--
作者：
Williams, Bethan A.;Walker, Daniel L.;Longmore, Steven N.;Barnes, A. T.;Battersby, Cara;Garay, Guido;Ginsburg, Adam;Gomez, Laura;Henshaw, Jonathan D.;Ho, Luis C.
年轻大质量星团 (YMC) 是致密 (≲1 pc)、高质量 (>104M⊙) 的恒星系统，具有重大科学意义。由于它们的稀有性和快速形成，在恒星形成开始之前，我们很少有 YMC 祖气体云的例子。因此，YMC形成所需的初始条件是不确定的。我们提供高分辨率（0.13角秒，∼1000 au）ALMA观测和Mopra单碟数据，表明银河中心尘埃脊“云d”（G0.412+0.052，质量= 7.6×104M⊙，半径= 3.2 pc）有潜力成为类似拱门的YMC (104M⊙,r∼ 1 pc)，但尚未形成恒星。这意味着它是已知的最年轻的恒星形成前大质量星团，因此可能是研究 YMC 形成初始条件的理想实验室。我们在尘埃连续体中发现了 96 个源，质量为 ≲3 M⊙，半径为 ∼103au。源质量和分离与热破碎比与湍流破碎更一致。由于维里参数估计的不确定性很大，因此不可能明确确定大多数源的动态状态。我们发现了大规模（∼1 pc）汇聚气流的证据，这可能导致云快速增长，在 105 年内增加 104M⊙。最高密度的气体出现在大规模流动的汇聚点处。我们预计这个星云会形成许多大质量恒星，但没有发现大质量无恒星核心。如果源代表恒星形成的初始条件，则所得的初始质量函数将是底部重的。
Young massive clusters (YMCs) are compact (≲1 pc), high-mass (>104M⊙) stellar systems of significant scientific interest. Due to their rarity and rapid formation, we have very few examples of YMC progenitor gas clouds before star formation has begun. As a result, the initial conditions required for YMC formation are uncertain. We present high resolution (0.13 arcsec, ∼1000 au) ALMA observations and Mopra single-dish data, showing that Galactic Centre dust ridge ‘Cloud d’ (G0.412 + 0.052, mass = 7.6 × 104M⊙, radius = 3.2 pc) has the potential to become an Arches-like YMC (104M⊙,r∼ 1 pc), but is not yet forming stars. This would mean it is the youngest known pre-star-forming massive cluster and therefore could be an ideal laboratory for studying the initial conditions of YMC formation. We find 96 sources in the dust continuum, with masses ≲3 M⊙and radii of ∼103au. The source masses and separations are more consistent with thermal rather than turbulent fragmentation. It is not possible to unambiguously determine the dynamical state of most of the sources, as the uncertainty on virial parameter estimates is large. We find evidence for large-scale (∼1 pc) converging gas flows, which could cause the cloud to grow rapidly, gaining 104M⊙within 105yr. The highest density gas is found at the convergent point of the large-scale flows. We expect this cloud to form many high-mass stars, but find no high-mass starless cores. If the sources represent the initial conditions for star formation, the resulting initial mass function will be bottom heavy.