The G305 star-forming complex: the central star clusters Danks 1 and Danks 2 The young star clusters Danks 1 and Danks 2
The G305 star-forming complex: the central star clusters Danks 1 and Danks 2 The young star clusters Danks 1 and Danks 2
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G305 恒星形成复合体：中央星团 Danks 1 和 Danks 2 年轻星团 Danks 1 和 Danks 2
DOI：
10.1111/j.1365-2966.2011.19736.x
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发表时间：
2012
影响因子：
4.8
通讯作者：
Davies B
中科院分区：
文献类型：
--
作者：
Davies B
G305 Hiicomplex (G305.4+0.1) 是银河系中迄今为止发现的最大的恒星形成结构之一。它是许多处于形成和演化各个阶段的大质量恒星的宿主，从嵌入式分子核心到后主序星。在这里，我们利用哈勃太空望远镜+NICMOS成像和甚大望远镜+ISAAC光谱对两个中心星团Danks 1和Danks 2进行了详细的近红外分析。我们发现到簇的分光光度距离与到 G305 复合体的运动距离一致，所有测量的平均值给出的距离为 3.8 ± 0.6 kpc。通过对恒星群和前主序恒星的分析，我们发现Danks 2是两个星团中最年长的，年龄为3+3− 1Myr。 Danks 1 显然更年轻，年龄为 1.5+1.5− 0.5Myr，主要由三颗非常明亮的富 H 沃尔夫-拉叶星组成，其质量可能为 ≳100 M⊙。这两个星团的质量函数与 Salpeter 斜率一致，Danks 1 和 Danks 2 的总星团质量分别为 8000 ± 1500 和 3000 ± 800 M⊙。 Danks 1 明显是两者中更紧凑的星团，并且是银河系中最密集的星团之一，其 log (ρ/M⊙pc−3) = 5.5+0.5− 0.4。除了星团之外，分子云的空腔内还有一群明显孤立的沃尔夫-拉叶星。我们的结果表明，G305 的恒星形成历史始于 Danks 2 的形成，随后是 Danks 1 的形成，而弥散进化群体的起源目前尚不确定。 G305 区域中心的大质量恒星似乎正在清除原生星云的剩余部分，从而引发星云外围的新一代恒星形成。
The G305 Hiicomplex (G305.4+0.1) is one of the most massive star-forming structures yet identified within the Galaxy. It is host to many massive stars at all stages of formation and evolution, from embedded molecular cores to post-main-sequence stars. Here, we present a detailed near-infrared analysis of the two central star clusters Danks 1 and Danks 2, usingHubble Space Telescope+NICMOS imaging and Very Large Telescope+ISAAC spectroscopy. We find that the spectrophotometric distance to the clusters is consistent with the kinematic distance to the G305 complex, an average of all measurements giving a distance of 3.8 ± 0.6 kpc. From analysis of the stellar populations and the pre-main-sequence stars, we find that Danks 2 is the elder of the two clusters, with an age of 3+3− 1Myr. Danks 1 is clearly younger with an age of 1.5+1.5− 0.5Myr, and is dominated by three very luminous H-rich Wolf–Rayet stars which may have masses ≳100 M⊙. The two clusters have mass functions consistent with the Salpeter slope, and total cluster masses of 8000 ± 1500 and 3000 ± 800 M⊙for Danks 1 and Danks 2, respectively. Danks 1 is significantly the more compact cluster of the two, and is one of the densest clusters in the Galaxy with log (ρ/M⊙pc−3) = 5.5+0.5− 0.4. In addition to the clusters, there is a population of apparently isolated Wolf–Rayet stars within the molecular cloud’s cavity. Our results suggest that the star-forming history of G305 began with the formation of Danks 2, and subsequently Danks 1, with the origin of the diffuse evolved population currently uncertain. Together, the massive stars at the centre of the G305 region appear to be clearing away what is left of the natal cloud, triggering a further generation of star formation at the cloud’s periphery.