銀河中心での階層的クラスター形成が巨大星の誕生を促進(Hierarchical Cluster Formation in the Galaxy’s Core Caps Birth of Massive Stars)

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2025-04-03 中国科学院(CAS)

中国科学院上海天文台の張穗南博士が率いる国際研究チームは、銀河中心分子帯(CMZ)における星形成の独特なメカニズムを明らかにしました。ALMA望遠鏡を用いた観測により、CMZでは極度の乱流がガスを細かく分断し、「階層的」な星団形成が進行し、大質量星の誕生が抑制されていることが判明。数百AU規模の星の「胚」クラスターが確認され、将来的に大質量星系へ進化する可能性も示されました。これは、極限環境下での星形成理解や他銀河の中心領域、初期宇宙における星形成研究にも貢献する成果です。

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中央分子領域の3つのプロトクラスターにおけるサブクラスター化と星形成効率 Subclustering and Star Formation Efficiency in Three Protoclusters in the Central Molecular Zone

Suinan Zhang (张遂楠), Xing Lu (吕行), Adam Ginsburg, Nazar Budaiev, Yu Cheng, Hauyu Baobab Liu, Tie Liu, Qizhou Zhang, Keping Qiu, Siyi Feng,…
The Astrophysical Journal Letters
DOI:10.3847/2041-8213/adb30b

銀河中心での階層的クラスター形成が巨大星の誕生を促進(Hierarchical Cluster Formation in the Galaxy’s Core Caps Birth of Massive Stars)

Abstract

We present the highest-resolution (∼0.′′04) Atacama Large Millimeter/submillimeter Array 1.3 mm continuum observations so far of three massive star-forming clumps in the Central Molecular Zone (CMZ), namely 20 km s−1 C1, 20 km s−1 C4, and Sgr C C4, which reveal prevalent compact millimeter emission. We extract the compact emission with astrodendro and identify a total of 199 fragments with a typical size of ∼370 au, which represent the first sample of candidates of protostellar envelopes and disks and kernels of prestellar cores in these clumps that are likely forming star clusters. Compared with the protoclusters in the Galactic disk, the three protoclusters display a higher level of hierarchical clustering, likely a result of the stronger turbulence in the CMZ clumps. Compared with the mini-starbursts in the CMZ, Sgr B2 M and N, the three protoclusters also show stronger subclustering in conjunction with a lack of massive fragments. The efficiency of high-mass star formation of the three protoclusters is on average 1 order of magnitude lower than that of Sgr B2 M and N, despite a similar overall efficiency of converting gas into stars. The lower efficiency of high-mass star formation in the three protoclusters is likely attributed to hierarchical cluster formation.

1701物理及び化学
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