共查询到19条相似文献,搜索用时 109 毫秒
1.
整理汇集了迄今最完整的同时具备绝对自行与视向速度数据的144个疏散星团样本,计算得出这些星团的3维空间速度。对银河系疏散星团的空间分布(采用了更多样本)和运动学性质进行了若干统计分析。 相似文献
2.
准确的成员判定是星团蓝离散星研究的首要问题。本利用星团的测光、自行和视向速度等数据及观测资料,对10个较年老的疏散星团进行了蓝离散星的证认和成员确定工作,从而为进一步的研究提供了较纯的星团蓝离散星样本。 相似文献
3.
疏散星团是探究银河系结构与演化的良好示踪体,一直以来颇受关注.之前关于疏散星团的研究中,仅有一小部分疏散星团有金属丰度参数,而且,金属丰度的测量,是基于不同质量的观测数据,采用了不同的方法.收集了一个年龄大于2 Gyr的老年疏散星团样本,通过整理这些星团成员星的金属丰度数据,一方面,以星团NGC 2682为例,对比了不同光谱巡天项目给出的星团成员星金属丰度的系统差异;另一方面,计算了星团成员星金属丰度的平均值和中位值,作为该疏散星团的金属丰度推荐值.此外,还利用该样本探究了银盘径向金属丰度梯度随时间的演化,结果表明,早期银盘有着更加陡峭的径向金属丰度梯度,随着演化时间的增加,银盘径向金属丰度梯度逐渐趋于平缓,为银盘化学演化模型提供了更加严格的观测约束. 相似文献
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整理汇集了同时具备距离、年龄与金属丰度数据的疏散星团样本,共计118个。利用这些资料,对银河系疏散星团的金属丰度分布性质进行了若干统计分析,进一步研究了银盘径向金属丰度梯度随时间和空间的演化情况,并对银盘年龄-金属丰度关系作了讨论。 相似文献
6.
该文利用疏散星团NGC 6530的自行观测数据和成员判别结果,给出了星团的光度函数,并详细讨论了星团的质量分层效应。分析表明,NGC 6530存在空间质量分层效应,但并不存在速度质量分层,因此星团的表观空间质量分层可能起因于星团形成时的初始条件,而不是动力学弛豫的结果。 相似文献
7.
本文利用疏散昨团NGC2286天区内250颗恒星的相对自行及成员概率判定资料,首次对该星团的半径、光度函数以及内部运动等做较深入的研究,分析表明对NGC2286这个中等年龄的星团,正处于动力学演化的初级阶段,在空间和速度上都没有表现出象年老疏散星团M67那样较为明显的分层效应。 相似文献
8.
利用绝对自行资料,确定了年轻疏散星团NGC 2244天区恒星的运动学成员概率,并对星团成员概率以及自行矢量的分布、不同成员概率恒星的位置分布情况、径向数密度轮廓等进行了讨论并给出了星团的特征尺度;进一步结合已知的星团距离和视向速度资料,计算了NGC 2244的三维空间运动速度,结果表明NGC 2244是一个典型的薄盘族星团。 相似文献
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在合理假设星团成员星的内部随机运动为各向同性的基础上,提出一种利用纯运动学资料确定星团距离的方法,并依此方法估算出疏散星团M11的速度距离为(1.89±0.52)kpc。这一结果与其他作者给出的星团M11的光度距离符合得相当好。 相似文献
10.
巨蟹座中除了著名的蜂巢星团M44之外,还有一个疏散星团M67也很有名。据天文学家们估算,它的年龄在50亿年以上,是银河系中最老的疏散星团之一。它也是所有疏散星团中研究得最广泛,获得有关恒星演化和星团年龄的信息最多的一个星团,格外受到天文学家的关注。最... 相似文献
11.
S. Rser N.V. Kharchenko A.E. Piskunov E. Schilbach R.‐D. Scholz H. Zinnecker 《Astronomische Nachrichten》2010,331(5):519-525
It is textbook knowledge that open clusters are conspicuous members of the thin disk of our Galaxy, but their role as contributors to the stellar population of the disk was regarded as minor. Starting from a homogenous stellar sky survey, the ASCC‐2.5, we revisited the population of open clusters in the solar neighbourhood from scratch. In the course of this enterprise we detected 130 formerly unknown open clusters, constructed volume‐ and magnitude‐limited samples of clusters, re‐determined distances, motions, sizes, ages, luminosities and masses of 650 open clusters. We derived the present‐day luminosity and mass functions of open clusters (not the stellar mass function in open clusters), the cluster initial mass function CIMF and the formation rate of open clusters. We find that open clusters contributed around 40 percent to the stellar content of the disk during the history of our Galaxy. Hence, open clusters are important building blocks of the Galactic disk (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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R. de la Fuente Marcos C. de la Fuente Marcos D. Reilly 《Astrophysics and Space Science》2014,349(1):379-400
Historically, it has been assumed that globular and open clusters never interact. However, recent evidence suggests that: globular clusters passing through the disk may be able to perturb giant molecular clouds (GMCs) triggering formation of open clusters and some old open clusters may be linked to accreted globulars. Here, we further explore the existence of possible dynamical connections between globular and open clusters, and realize that the most obvious link must be in the form of gravitational interactions. If open clusters are born out of GMCs, they have to move in similar orbits. If we accept that globulars can interact with GMCs, triggering star formation, it follows that globular and open clusters must also interact. Consistently, theoretical arguments as well as observational evidence, show that globular and open clusters certainly are interacting populations and their interactions are far more common than usually thought, especially for objects part of the bulge/disk. Monte Carlo calculations confirm that conclusion. Globular clusters seem capable of not only inducing formation of open clusters but, more often, their demise. Relatively frequent high speed cluster encounters or cluster harassment may also cause, on the long-term, slow erosion and tidal truncation on the globulars involved. The disputed object FSR 1767 (2MASS-GC04) may be, statistically speaking, the best example of an ongoing interaction. 相似文献
13.
使用上海天文台佘山40cm折射望远镜拍摄的底片资料,对球状星团M79中心附近15’×15’天区内106颗恒星和63颗Tycho-2星,以《Tycho-2星表》中M79附近1°×1°天区内上述63颗Ty cho-2星的位置和自行为参考,归算得到了所有169颗恒星的位置和自行,并估计了其成员概率。 相似文献
14.
Abundance Gradient from Open Clusters and Implications for the Galactic Disk Evolution 总被引:3,自引:0,他引:3
Jin-Liang Hou * Rui-Xiang Chang Li Chen Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai National Astronomical Observatories Chinese Academy of Sciences Beijing Galactic structure dynamics Received Jun 《中国天文和天体物理学报》2002,2(1):17-32
1 INTRODUCTIONRadial abundance gradient along the Galactic disk constitutes one of the most importantobservational constraillts fOr models of the evolution of the Galactic disk. The existence of sucha gradient is now well established, through radio and optical observations of HII regions, diskstars, pIanetary nebulae (see Henry and Worthey 1999 for a detailed review) and open clusters(Friel 1995, 1999). An average gradiellt of dlog(X/H)/dR ~ --0.06 dex kpc--' is observed inthe Milky … 相似文献
15.
With the advent of either sensitive space-born infrared cameras, or their high-resolution ground-based siblings, we are uncovering
a new category of star clusters: the dust-enshrouded super-star clusters. These manifest themselves only beyond a few microns,
as their shroud of dust is able to block all light emitted by the stars themselves. Here we present our results on the spectacular
cluster in SBS 0335-052, a very metal-poor galaxy. We also point to the growing number of galaxy analogs to SBS 0335-052,
revealing the possibility that these clusters signal a major mode of star formation in starbursts. We conclude by listing
a number of open points these clusters raise, in particular with respect to high-redshift counterparts.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
利用上海天文台的照相底片资料,确定了疏散星团NGC6530天区364颗恒星的自行和成员概率,并对有关自行测定的方法、结果和精度等问题作了较为详细的介绍和讨论。使用的底片历元差为87年,全部恒星自行中误差的均方根值为1.09mas/a。 相似文献
17.
Based on published data, we have compiled a catalogue of fundamental astrophysical parameters for 593 open clusters of the Galaxy. In particular, the catalogue provides the Galactic orbital elements for 500 clusters, the masses, central concentrations, and ellipticities for 424 clusters, the metallicities for 264 clusters, and the relative magnesium abundances for 56 clusters. We describe the sources of initial data and estimate the errors in the investigated parameters. The selection effects are discussed. The chemical and kinematical properties of the open clusters and field thin-disk stars are shown to differ. We provide evidence for the heterogeneity of the population of open star clusters. 相似文献
18.
W. Gtz 《Astronomische Nachrichten》1986,307(6):371-378
The noteworthy deviations and differences given in the individual values of the metal abundance of open clusters were studied. It could be shown that the metal abundance of open clusters, which are situated in or near the galactic plane (|z| ≦ 0.3 Kpc) are not only correlated wiht the galactocentric distance (RGC ) but also with the galactic longitude l of the clusters. This correlation is not given in the open clusters of high |z|-distances. There, the metal abundance is connected as well with the galactocentric radius (RGC ) as with the distances of the objects form the galactic plane. 相似文献
19.
Shuang Gao Bi-Wei Jiang Yong-Heng Zhao Department of Astronomy Beijing Normal University Beijing National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2007,7(1):111-119
1 INTRODUCTION The globular cluster (GC hereafter), as the oldest star group in the universe, has been a target that astro- physics has paid close attention to all the time. The near-field (Galaxy) cosmology makes contacts with the far-field cosmology by … 相似文献