CHEMODYNAMICS OF COMPACT STELLAR SYSTEMS IN NGC 5128: HOW SIMILAR ARE GLOBULAR CLUSTERS, ULTRA-COMPACT DWARFS, AND DWARF GALAXIES?
CHEMODYNAMICS OF COMPACT STELLAR SYSTEMS IN NGC 5128: HOW SIMILAR ARE GLOBULAR CLUSTERS, ULTRA-COMPACT DWARFS, AND DWARF GALAXIES?
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DOI：
10.1088/0004-637x/712/2/1191
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
Matthew A. Taylor;T. Puzia;G. Harris;W. Harris;M. Kissler-Patig;M. Hilker
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文献类型：
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作者：
Matthew A. Taylor;T. Puzia;G. Harris;W. Harris;M. Kissler-Patig;M. Hilker
本文介绍了NGC 5128（半人马座A）中几个最明亮的球状星团（GCs）的速度色散测量，这些光谱是用8.2 m ESO/甚大望远镜上的UVES梯队光谱仪获得的高分辨率光谱。测量使用惩罚像素拟合方法，参数化地恢复视线速度色散。将测量到的速度色散与哈勃太空望远镜的表面光度测定和结构参数数据相结合，可以推导出动态质量和质量光比。这些大质量恒星系统的性质与本星系群、核星团和超紧凑矮星系（ucd）中的大质量GCs相似。研究了这些星系团的基本平面关系，以填补本群GCs与更大质量早型星系之间的明显空白。研究发现，这些大质量恒星系统的性质与矮椭圆星系和ucd中的核星团的性质比局域群GCs中的核星团的性质更吻合，并且所有天体都具有相似的年龄（> 8 Gyr），这表明矮椭圆星系（dE,Ns）、ucd和大质量GCs中的核星团的形成和演化可能存在联系。我们发现动态质量-光比和M☉以上形式的动态质量之间有非常陡峭的相关性。利用根据Lick/IDS指标系统校准的吸收线强度，对地层进行化学丰度分析。结果支持了包含在单一一般地层方案中的两种情况。古老的、大质量的超级太阳[α/Fe]系统是在短时间（小于100 Myr）内通过单坍缩gc的合并形成的，而单坍缩gc本身是在单个巨大的分子云中形成的。更多的中老年（~ 3-10 Gyr），太阳到亚太阳[α/Fe]系统是在更长的（~ Gyr）时间尺度上通过在1013-1015 M☉的大质量星系和星系团的势阱中剥离dE，Ns而形成的。
Velocity dispersion measurements are presented for several of the most luminous globular clusters (GCs) in NGC 5128 (Centaurus A) derived from high-resolution spectra obtained with the UVES echelle spectrograph on the 8.2 m ESO/Very Large Telescope. The measurements are made utilizing a penalized pixel-fitting method that parametrically recovers line-of-sight velocity dispersions. Combining the measured velocity dispersions with surface photometry and structural parameter data from the Hubble Space Telescope enables both dynamical masses and mass-to-light ratios to be derived. The properties of these massive stellar systems are similar to those of both massive GCs contained within the Local Group and nuclear star clusters and ultra-compact dwarf galaxies (UCDs). The fundamental plane relations of these clusters are investigated in order to fill the apparent gap between the relations of Local Group GCs and more massive early-type galaxies. It is found that the properties of these massive stellar systems match those of nuclear clusters in dwarf elliptical galaxies and UCDs better than those of Local Group GCs, and that all objects share similarly old (≳8 Gyr) ages, suggesting a possible link between the formation and evolution of nuclear star clusters in dwarf elliptical galaxies (dE,Ns), UCDs, and massive GCs. We find a very steep correlation between dynamical mass-to-light ratio and dynamical mass of the form above M☉. Formation scenarios are investigated with a chemical abundance analysis using absorption-line strengths calibrated to the Lick/IDS index system. The results lend support to two scenarios contained within a single general formation scheme. Old, massive, super-solar [α/Fe] systems are formed on short (≲100 Myr) timescales through the merging of single-collapse GCs which themselves are formed within single, giant molecular clouds. More intermediate- and old-aged (∼3–10 Gyr), solar- to sub-solar [α/Fe] systems are formed on much longer (∼Gyr) timescales through the stripping of dE,Ns in the 1013–1015 M☉ potential wells of massive galaxies and galaxy clusters.