我们总结了最近的大质量恒星形成区域天蝎座-半人马座OB星协（Sco OB 2）的恒星星族和恒星形成历史的观测结果。它由三个亚群组成，上天蝎座（US），上半人马座-狼疮（UCL）和下半人马座-十字座（LCC），年龄约为5，17，160万年。在上天蝎座，许多研究最近揭示了数百个低质量的协会成员，包括数十个褐矮星。经验质量函数可以在0.1 M_sun到20 M_sun的整个恒星质量范围内建立，并且被发现与最近确定的场初始质量函数一致。低质量恒星的年龄在500万年左右，与先前（独立）推导出的高质量成员的年龄相同。这支持了早期的迹象，即美国的恒星形成过程被触发，并同意以前的说法，即触发事件是来自附近UCL群的超新星和风驱动的冲击波。在较老的UCL和LCC区域，最近在X射线和自行选择的候选者中确定了大量的低质量成员。在这两个亚群中，通过对更知名的区域（主要是狼疮和TW Hya协会）附近的X射线源的调查，也偶然发现了低质量成员。虽然这两个亚群的平均年龄似乎都在1600万年左右，但它们都显示出具有亚结构的迹象。它们的恒星形成历史可能比更年轻、更紧凑的美国集团更复杂。...（摘要缩写;完整摘要见论文）。
英文摘要：
We summarize observational results on the stellar population and star formation history of the Scorpius-Centaurus OB Association (Sco OB2), the nearest region of recent massive star formation. It consists of three subgroups, Upper Scorpius (US), Upper Centaurus-Lupus (UCL), and Lower Centaurus-Crux (LCC) which have ages of about 5, 17, and 16 Myr. In Upper Scorpius, numerous studies have recently revealed hundreds of low-mass association members, including dozens of brown dwarfs. The empirical mass function could be established over the full stellar mass range from 0.1 M_sun up to 20 M_sun, and was found to be consistent with recent determinations of the field initial mass function. A narrow range of ages around 5 Myr was found for the low-mass stars, the same age as had previously (and independently) been derived for the high-mass members. This supports earlier indications that the star formation process in US was triggered, and agrees with previous conjectures that the triggering event was a supernova- and wind-driven shock-wave originating from the nearby UCL group. In the older UCL and LCC regions, large numbers of low-mass members have recently been identified among X-ray and proper-motion selected candidates. In both subgroups, low-mass members have also been serendipitously discovered through investigations of X-ray sources in the vicinity of better known regions (primarily the Lupus and TW Hya associations). While both subgroups appear to have mean ages of ~16 Myr, they both show signs of having substructure. Their star-formation histories may be more complex than that of the younger, more compact US group. ... (abstract abbreviated; see paper for full abstract).
A Large-Area Search for Low Mass Objects in Upper Scorpius I: The Photometric Campaign and New Brown Dwarfs
我们对上天蝎座OB星协进行了一次覆盖~200 deg^2的宽视场光度测量。Palomar 48英寸望远镜上Quest-2相机在R和I波段拍摄的数据与2 MASS JHK巡天结合起来，用于选择候选的前主序星。后续光谱与帕洛玛200英寸望远镜的62个候选晚型成员确定了43颗恒星，其表面重力特征与协会成员一致。从光学/近红外测光和衍生的光谱类型，我们构建了一个HR图的新成员，并找到30个可能的新棕矮星，几乎是已知的上天蝎座OB协会的亚恒星人口的两倍。继续我们的光谱运动应该揭示数百个新的恒星和亚恒星成员。
Spectroscopic identification of DENIS-selected brown dwarf candidates in the Upper Scorpius OB association
我们对上天蝎座OB星协中40个候选极低质量成员进行了低分辨率（R=900）光学（576.1- 1，051.1 nm）光谱观测。使用DENIS数据库中可用的$I$、$J$和$K$测光选择这些物体。我们已经推导出光谱类型，我们已经测量了H $α$和NaI双峰（在818.3和819.5 nm）的等效宽度。我们评估的对象的青年，通过比较他们的老同行的类似光谱类型的昴星团和外地。我们的分析表明，我们的目标中有28个是年轻的非常低质量的物体，因此它们是OB协会的强候选成员。其他12个DENIS源是前景M矮星或背景红巨星。我们的光谱候选成员样本包括18个光谱类型在M6.5和M9范围内的天体，它们可能是年轻的棕矮星。我们使用Barrado y Navascués & Mart 'ın（2003）提出的方案将这些候选物分类为吸积/非吸积。我们发现5个亚恒星质量的候选星团成员仍在进行质量吸积，这表明在某些情况下，吸积到棕矮星上的时间尺度可以长达500万年。
