Old open clusters in the inner Galaxy: FSR 1744, FSR 89 and FSR 31
Old open clusters in the inner Galaxy: FSR 1744, FSR 89 and FSR 31
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银河系内部的古老疏散星团：FSR 1744、FSR 89 和 FSR 31
DOI：
10.1051/0004-6361:20077675
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发表时间：
2007
影响因子：
6.5
通讯作者：
E. Bica
中科院分区：
文献类型：
--
作者：
C. Bonatto;E. Bica
上下文我们研究了在银河系内部的中/老疏散星团的动态生存。目标。我们的目标是确定最近编目的物体FSR 1744、FSR 89和FSR 31的性质并推导其基本和结构参数，以限制银河潮汐扰动效率，改进疏散星系团参数空间的统计数据，并更好地定义它们的年龄分布函数在太阳内部圆。讨论了内银河系中发现的疏散星团数量少的问题的现状。方法.利用2 MASS色星等图和场星星去污光度法建立的恒星径向密度分布图研究了天体的性质。结构参数的诊断图被用来区分影响这种中心投射疏散星团的动力学和高背景效应。结果FSR 1744、FSR 89和FSR 31是Gyr-class疏散星团，距离银河中心4.0-5.6 kpc。与附近的疏散星团相比，它们的核心半径和极限半径都很小。结论.关于在银河系内部观察到的少数疏散星团，近红外线中出现的情况有利于动力学演化驱动的破坏，而不是与吸收和/或高背景水平相关的观测限制。在内部，与动力学演化相关的主要过程是恒星演化引起的质量损失、质量分离和蒸发。在外部，它们是来自盘和凸起的潮汐应力，以及与巨大分子云的相互作用。FSR 1744、FSR 89和FSR 31的结构参数与它们的银心距离一致，在这个意义上，潮汐诱导效应可能加速了动力学演化。
Context. We examine the dynamical survival of intermediate-age/old open clusters in the inner Galaxy. Aims. We aim to establish the nature and derive fundamental and structural parameters of the recently catalogued objects FSR 1744, FSR 89 and FSR 31 to constrain the Galactic tidal disruption efficiency, improve statistics of the open cluster parameter space, and better define their age-distribution function inside the Solar circle. The current status of the issue dealing with the small number of detected open clusters in the inner Galaxy is discussed. Methods. Properties of the objects are investigated with 2MASS colour–magnitude diagrams and stellar radial density profiles built with field star decontaminated photometry. Diagnostic diagrams of structural parameters are used to separate dynamical from highbackground effects affecting such centrally projected open clusters. Results. FSR 1744, FSR 89 and FSR 31 are Gyr-class open clusters located at Galactocentric distances 4.0–5.6 kpc. Compared to nearby open clusters, they have small core and limiting radii. Conclusions. With respect to the small number of open clusters observed in the inner Galaxy, the emerging scenario in the nearinfrared favours disruption driven by dynamical evolution rather than observational limitations associated with absorption and/or high background levels. Internally, the main processes associated with the dynamical evolution are mass loss by stellar evolution, mass segregation and evaporation. Externally they are tidal stress from the disk and bulge, and interactions with giant molecular clouds. FSR 1744, FSR 89 and FSR 31 have structural parameters consistent with their Galactocentric distances, in the sense that tidally induced effects may have accelerated the dynamical evolution.