A revisit to agglomerates of early-type Hipparcos stars
A revisit to agglomerates of early-type Hipparcos stars
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重新审视早期依帕谷恒星团聚体
DOI：
10.1002/asna.200811024
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
L. Dinis
中科院分区：
文献类型：
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作者：
José A. Caballero;L. Dinis
研究了依巴谷蓝B_T-V_T星富集区的空间结构和亚结构。这些区域包括大型恒星复合体、OB星协和年轻的疏散星团，它们是银河系中正在形成的星星的示踪物。DBSCAN（Density-Based Spatial Clustering of Applications with Noise）数据聚类算法用于寻找早期型恒星的空间超密度。一旦一个密度过高的“聚集体”被识别出来，我们就对他们的星星成员候选人进行数据和书目汇编。每个早期型星星的实际成员在凝聚的基础上，它的日心距，自行和以前的分光光度信息进行了研究。我们确定了35个早期依巴谷型恒星的聚集体。它们中的大多数与以前已知的集群和OB协会。以前未知的P Puppis凝聚物是虚拟天文台工具专门研究的主题。它实际上是一个新的、邻近的、年轻的疏散星团（d ~ 470 pc，年龄~ 20 Ma），具有明显的径向密度梯度。我们列出Puppis和其他六个聚集体（包括NGC 2451 A，vdBH 23和Trumpler 10）作为亚恒星搜索的新地点，因为它们的年轻，接近和空间密度。我们详细研究了猎户座，CMa-Pup和Pup-Vel OB复合物（“超级团聚体”）的子结构。我们确认或发现猎户座复合体中的一些恒星过密度，如25猎户座集团，马头区（包括猎户座sigma集群），和猎户座eta团聚。最后，我们得到了昴星团、NGC 2451 A和IC 2391的精确视差距离，描述了几颗d < 200 pc的场早型星，并讨论了我们搜索的不完整性。
We study the spatial structure and sub-structure of regions rich in Hipparcos stars with blue B_T-V_T colours. These regions, which comprise large stellar complexes, OB associations, and young open clusters, are tracers of on-going star formation in the Galaxy. The DBSCAN (Density-Based Spatial Clustering of Applications with Noise) data clustering algorithm is used to look for spatial overdensities of early-type stars. Once an overdensity, "agglomerate", is identified, we carry out a data and bibliographic compilation of their star member candidates. The actual membership in agglomerate of each early-type star is studied based on its heliocentric distance, proper motion, and previous spectro-photometric information. We identify 35 agglomerates of early-type Hipparcos stars. Most of them are associated to previously known clusters and OB associations. The previously unknown P Puppis agglomerate is subject of a dedicated study with Virtual Observatory tools. It is actually a new, nearby, young open cluster (d ~ 470 pc, age ~ 20 Ma) with a clear radial density gradient. We list P Puppis and other six agglomerates (including NGC 2451 A, vdBH 23, and Trumpler 10) as new sites for substellar searches because of their youth, closeness, and spatial density. We investigate in detail the sub-structure in the Orion, CMa-Pup and Pup-Vel OB complexes ("super-agglomerates"). We confirm or discover some stellar overdensities in the Orion complex, like the 25 Ori group, the Horsehead region (including the sigma Orionis cluster), and the eta Orionis agglomerate. Finally, we derive accurate parallactic distances to the Pleiades, NGC 2451 A, and IC 2391, describe several field early-type stars at d < 200 pc, and discuss the incompleteness of our search.