FSR 584 – a new globular cluster in the Galaxy?
FSR 584 – a new globular cluster in the Galaxy?
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FSR 584——银河系中的一个新球状星团？
DOI：
10.1051/0004-6361:20078029
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发表时间：
2007
影响因子：
6.5
通讯作者：
B. Barbuy
中科院分区：
文献类型：
--
作者：
E. Bica;C. Bonatto;S. Ortolani;B. Barbuy
目标。我们研究了最近编目的候选星星星团FSR 584的性质，它被投射到分子云W3的方向，可能是离太阳最近的球状星团。方法. 2 MASS色星等图、恒星径向密度剖面和自行被用来导出基本参数和结构参数。结果色星等图形态和径向密度剖面显示FSR 584是一个古老的星星团。在自行的情况下，FSR 584的性质与贫金属（[Fe/H] δ-2）球状星团一致，具有明确的转折点和蓝色水平分支的证据。FSR 584可能是一个类似Palomar的晕球状星团，正在向银河平面移动，目前在银河平面上方1.20秒差距处。与太阳的距离为d 1.4千秒差距，位于太阳圈外1.21千秒差距处。径向密度分布的特征在于核心半径R核心= 0.3 ± 0.1 pc。然而，我们不能排除旧疏散星团的可能性。结论.近红外测光结合自行支持FSR 584是银河系中一个新的球状星团的假设。它的吸收率为A v = 9.2 ± 0.6，这使它成为光学上的一个限制性物体，并解释了为什么它迄今为止一直被忽视。
Aims. We investigate the nature of the recently catalogued star cluster candidate FSR 584, which is projected in the direction of the molecular cloud W 3 and may be the nearest globular cluster to the Sun. Methods. 2MASS colour-magnitude diagrams, the stellar radial density profile, and proper motions are employed to derive fundamental and structural parameters. Results. The colour-magnitude diagram morphology and the radial density profile show that FSR584 is an old star cluster. With proper motions, the properties of FSR 584 are consistent with a metal-poor ([Fe/H] ≈ -2) globular cluster with a well-defined turnoff and evidence of a blue horizontal-branch. FSR 584 might be a Palomar-like halo globular cluster that is moving towards the Galactic plane, currently at ≈20 pc above it. The distance from the Sun is d ⊙ ≈ 1.4 kpc, and it is located at ≈ 1 kpc outside the Solar circle. The radial density profile is characterized by a core radius of R core = 0.3 ± 0.1 pc. However, we cannot exclude the possibility of an old open cluster. Conclusions. Near-infrared photometry coupled to proper motions support the scenario where FSR 584 is a new globular cluster in the Galaxy. The absorption is A v = 9.2 ± 0.6, which makes it a limiting object in the optical and explains why it has so far been overlooked.