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球状星团M3的绝对自行测定及其空间运动 总被引:2,自引:0,他引:2
使用上海天文台佘山40厘米折射望远镜拍摄的两期共14张球状星团M3底片的PDS扫描结果,以ACT星表中的24颗恒星的位置和绝对自行为参考架,用中心重叠法进行天体测量归算,得到了这个星团中心附近1°5.5x1°.5天区内534颗恒星的位置和绝对自行,并利用这些自行对成员概率进行估算,得到这个星团的赤经方向绝对自行为-0.3±0.3mas/yr,赤纬方向绝对自行为-3.1±0.3mas/yr.使用该自行值,结合已知的M3的距离和视向速度,计算了其在给定的银河系引力势中的运动轨道. 相似文献
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《天文学进展》2020,(2)
球状星团是银河系中最古老的天体系统之一,其恒星密度极端高的核心有利于创造双星之间进行物质交换的环境,从而形成毫秒脉冲星双星、掩食脉冲双星、主序-毫秒脉冲双星、高轨道偏心率双星等双星系统,通过对这些系统进行研究有助于进一步认识球状星团的动力学、双星系统的演化和星际介质等相关问题。自30年前在球状星团中发现第一颗射电脉冲星至今,随着较高灵敏度射电望远镜的不断建成和使用,以及数据数字化处理能力的提高,天文学家在球状星团射电脉冲星的观测和理论研究方面取得很大进展。收集并分析了最新的球状星团脉冲星的数据,研究了球状星团射电脉冲星的自转周期和轨道周期的基本性质,讨论了球状星团脉冲星的搜寻,最后统计分析了双星系统,包括不同伴星类型的脉冲星的分布以及掩食双星系统的性质。 相似文献
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简述了精确测定相对自行的方法,特别介绍了在用2~3个历元的底片和CCD观测结果推导恒星自行的过程中如何消除光学视场畸变、星等差和色差的具体办法;并介绍了用星系把相对自行推算绝对自行的方法。还介绍了用自行资料研究银河系结构和演化的一些前沿课题,其中包括星团研究、与银河系兼并的矮星系的发现、暗物质的检测、外星行星的探测和银河系中心黑洞的质量估算等。最后评价了自行在研究银河系中的重要性,论述了我国研制4m光学/近红外望远镜的重要意义。 相似文献
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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
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选取前文中所列出的29个累积光谱型为F型的球状星团中的3个作为样本,深入研究了初始观测资料的不确定性和选用不同的银河系引力势模型,对样本星团轨道参数的影响。首先采用Monte Carlo方法产生3个样本球状星团的模拟初始观测数据,而后,以这些模拟数据为初始条件,在3种不同的银河系引力势模型下进行轨道计算,得到此3个样本的模拟轨道参数。模拟计算的结果表明:根据模拟初始数据生成的样本轨道参数分布形态大致可分为高斯分布、准高斯分布和非高斯分布等3类;初始观测数据的不确定性对样本轨道参数分布的影响,与样本星团的选择和轨道参数的类型有关;选用不同的银河系引力势模型,对3个样本星团的各个轨道参数的分布和形态结构也会产生不同程度的影响。该工作的结果,可供深入研究球状星团的整体运动和动力学性质等问题参考。 相似文献
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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 14 4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
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Using astrometric plates of Shanghai Observatory spanning a period of 29 years, the absolute proper motion of the Galactic globular cluster M79 was measured. Adopting the distance and radial velocity given by Harris (1999), its present space velocity was derived; then by taking the Galactic gravitational potential model proposed by Allen and Santillan (1991), its past orbital parameters in the Galactic system were derived. We also discuss the uncertainties in kinematical studies of globular clusters based on the use of proper motion data. 相似文献
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Zhen-Yu Wu Jia-Ji Wang Li ChenShanghai Astronomical Observatory Chinese Academy of Sciences Shanghai National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2002,2(3):216-225
We examine 14 plates of the globular cluster M3 (NGC 5272) taken with the 40 cm refractor at the Sheshan station of Shanghai Astronomical Observatory. The plates span over a period of about 77 years. The positions and absolute proper motions of eight stars in the Hipparcos Catalogue and of 49 stars in the Tycho-2 Catalogue are used as the reference frame. The astrometric reduction is made with the central overlapping principle. The absolute proper motions of 534 stars in a region of about 100' × 100' around the cluster are measured. With the new proper motion data the membership probabilities of the stars are determined. The average absolute proper motion obtained for the cluster is -0.06@0.30 mas yr-1 in R.A. and -2.6@0.30 mas yr-1 in Decl. By combining this result with the known distance and radial velocity of the cluster, we also obtained the Galactic orbit of M3 for a chosen three-component Galactic potential. 相似文献
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Filippina Caputo 《Astronomy and Astrophysics Review》1998,9(1-2):33-61
The current knowledge of the evolution of Population II stars, as observed in galactic halos and globular clusters, is outlined.
The recent theoretical results provided by an improved physical understanding of the stars are reported, with a particular
emphasis upon those stellar evolutionary phases which are the keystones of the interpretation of globular cluster stars. Within
the up–to–date theoretical scenario, the luminosity of the turn–off stars and horizontal branch stars, which are of fundamental
importance for distance and age determinations, turns out to be fainter and brighter, respectively, in comparison with previous
theoretical computations. The predicted absolute magnitude of RR Lyrae stars is consistent with the bright values suggested from the long distance scale (Sandage 1993), but the slope of the relation between and metallicity ([Fe/H]) agrees with that suggested from the short distance scale (see, e.g., Carney et al. 1992, Clementini et al. 1995), at least with [Fe/H]-1.3. As to the globular cluster ages, the new computations provide younger ages ( 10 Gyr–13 Gyr), weakening the conflict with current cosmological estimates. The recent results derived from the fitting of
HIPPARCOS parallaxes of field subdwarfs to the fiducial main sequence of globular clusters are consistent with the up–to–date theoretical
models. However, the direct determinations of , which are based on the HIPPARCOS proper motions and trigonometric parallaxes of field RR Lyrae stars, give fainter absolute magnitudes than those obtained
from the improved evolutionary models. This seems to suggest that the problem of the globular cluster distance and age is
still open.
Received 6 April 1998 相似文献
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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
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A. A. Chemel E. V. Glushkova A. K. Dambis A. S. Rastorguev L. N. Yalyalieva A. D. Klinichev 《Astrophysical Bulletin》2018,73(2):162-177
We cross-match objects from several different astronomical catalogs to determine the absolute proper motions of stars within the 30-arcmin radius fields of 115 Milky-Way globular clusters with the accuracy of 1–2 mas yr?1. The proper motions are based on positional data recovered from the USNO-B1, 2MASS, URAT1, ALLWISE, UCAC5, and Gaia DR1 surveys with up to ten positions spanning an epoch difference of up to about 65 years, and reduced to Gaia DR1 TGAS frame using UCAC5 as the reference catalog. Cluster members are photometrically identified by selecting horizontal- and red-giant branch stars on color–magnitude diagrams, and the mean absolute proper motions of the clusters with a typical formal error of about 0.4 mas yr?1 are computed by averaging the proper motions of selected members. The inferred absolute proper motions of clusters are combined with available radial-velocity data and heliocentric distance estimates to compute the cluster orbits in terms of the Galactic potential models based on Miyamoto and Nagai disk, Hernquist spheroid, and modified isothermal dark-matter halo (axisymmetric model without a bar) and the same model + rotating Ferre’s bar (non-axisymmetric). Five distant clusters have higher-than-escape velocities, most likely due to large errors of computed transversal velocities, whereas the computed orbits of all other clusters remain bound to the Galaxy. Unlike previously published results, we find the bar to affect substantially the orbits of most of the clusters, even those at large Galactocentric distances, bringing appreciable chaotization, especially in the portions of the orbits close to the Galactic center, and stretching out the orbits of some of the thick-disk clusters. 相似文献
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This paper argues that the Milky Way galaxy is probably the largest member of the Local Group. The evidence comes from estimates of the total mass of the Andromeda galaxy (M31) derived from the three-dimensional positions and radial velocities of its satellite galaxies, as well as the projected positions and radial velocities of its distant globular clusters and planetary nebulae. The available data set comprises 10 satellite galaxies, 17 distant globular clusters and nine halo planetary nebulae with radial velocities. We find that the halo of Andromeda has a mass of together with a scalelength of 90 kpc and a predominantly isotropic velocity distribution. For comparison, our earlier estimate for the Milky Way halo is Although the error bars are admittedly large, this suggests that the total mass of M31 is probably less than that of the Milky Way . We verify the robustness of our results to changes in the modelling assumptions and to errors caused by the small size and incompleteness of the data set.
Our surprising claim can be checked in several ways in the near future. The numbers of satellite galaxies, planetary nebulae and globular clusters with radial velocities can be increased by ground-based spectroscopy, while the proper motions of the companion galaxies and the unresolved cores of the globular clusters can be measured using the astrometric satellites Space Interferometry Mission ( SIM ) and Global Astrometric Interferometer for Astrophysics ( GAIA ). Using 100 globular clusters at projected radii 20 R 50 kpc with both radial velocities and proper motions, it will be possible to estimate the mass within 50 kpc to an accuracy of 20 per cent. Measuring the proper motions of the companion galaxies with SIM and GAIA will reduce the uncertainty in the total mass caused by the small size of the data set to 22 per cent. 相似文献
Our surprising claim can be checked in several ways in the near future. The numbers of satellite galaxies, planetary nebulae and globular clusters with radial velocities can be increased by ground-based spectroscopy, while the proper motions of the companion galaxies and the unresolved cores of the globular clusters can be measured using the astrometric satellites Space Interferometry Mission ( SIM ) and Global Astrometric Interferometer for Astrophysics ( GAIA ). Using 100 globular clusters at projected radii 20 R 50 kpc with both radial velocities and proper motions, it will be possible to estimate the mass within 50 kpc to an accuracy of 20 per cent. Measuring the proper motions of the companion galaxies with SIM and GAIA will reduce the uncertainty in the total mass caused by the small size of the data set to 22 per cent. 相似文献
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N. R. Deacon N. C. Hambly R. R. King M. J. McCaughrean 《Monthly notices of the Royal Astronomical Society》2009,394(2):857-871
The UK Infrared Telescope Infrared Deep Sky Survey (UKIDSS) is the first of a new generation of infrared surveys. Here, we combine the data from two UKIDSS components, the Large Area Survey (LAS) and the Galactic Cluster Survey (GCS), with Two-Micron All-Sky Survey (2MASS) data to produce an infrared proper motion survey for low-mass stars and brown dwarfs. In total, we detect 267 low-mass stars and brown dwarfs with significant proper motions. We recover all 10 known single L dwarfs and the one known T dwarf above the 2MASS detection limit in our LAS survey area and identify eight additional new candidate L dwarfs. We also find one new candidate L dwarf in our GCS sample. Our sample also contains objects from 11 potential common proper motion binaries. Finally, we test our proper motions and find that while the LAS objects have proper motions consistent with absolute proper motions, the GCS stars may have proper motions which are significantly underestimated. This is possibly due to the bulk motion of some of the local astrometric reference stars used in the proper motion determination. 相似文献
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The study of the possible shapes of orbits of globular clusters of stars is closely connected with problems of studying the processes of formation and evolution of stars. The main difficulty in studying the orbits of these objects is the incompleteness of the information about the initial conditions of the motion, in particular the nearly complete absence of observational material on the proper motions of globular clusters. For that reason the study of the motion of these objects by direct dynamic methods has not yet succeeded. In such conditions it is necessary to resort to statistical methods developed by Edmondson and Von Hoerner, which make it possible to draw certain conclusions about the possible shapes of orbits of globular clusters on the basis of the Newtonian point-mass model.The purpose of this paper is to test the results of investigations of other authors against the latest observational data on globular clusters of stars and to develop the method itself further.Translated fromAstrofizika, Vol. 37, No. 4, 1994. 相似文献