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91.
Duncan A. Forbes G. K. T. Hau 《Monthly notices of the Royal Astronomical Society》2000,312(4):703-711
We present wide field-of-view near-infrared imaging from the NTT and very deep optical imaging from the HST of the young merging galaxy NGC 3597. The morphology of the galaxy and the properties of the newly formed protoglobular clusters (PGCs) are examined. Our K -band data reveal the presence of a second nucleus, which provides further evidence that NGC 3597 is the result of a recent merger. Combining new K -band photometry with optical photometry, we are able for the first time to derive a unique age for the newly formed PGCs of a few Myr. This is consistent with the galaxy starburst age of ≤10 Myr. From deep HST imaging, we are able to probe the luminosity function ∼8 magnitudes fainter than normal, old globular clusters, and confirm that the PGCs have a power-law distribution with a slope of ∼−2. 相似文献
92.
Y. Fukazawa K. Makishima T. Tamura K. Nakazawa H. Ezawa Y. Ikebe K. Kikuchi T. Ohashi 《Monthly notices of the Royal Astronomical Society》2000,313(1):21-31
We measured metal abundances of the intracluster medium in the central regions of 34 nearby clusters of galaxies, using ASCA data. Clusters that have a sharp X-ray emission centred on a cD galaxy are commonly found to exhibit a central increment in the Fe abundance, which is more pronounced in lower temperature clusters; +(0.1–0.2) solar at kT >5 keV, compared with +(0.2–0.3) solar at 1.5< kT <4 keV. These central excess metals are thought to be ejected from cD galaxies. Several low-temperature cD type clusters also show significant Si abundance increase by +(0.1–0.2) solar at the central region. Compared with the Si-rich abundances observed in the outer regions of rich clusters, the Si to Fe abundance ratio of central excess metals tends to be near the solar ratio, implying that type Ia products from cD galaxies are dominant for the central excess metals. On the other hand, some other clusters do not show the central Fe abundance increase. As these clusters tend to contain two or three central giant galaxies, it is suggested that galaxy interactions have removed the central abundance increase. 相似文献
93.
V. De Bruyne F. Leeuwin H. Dejonghe 《Monthly notices of the Royal Astronomical Society》2000,311(2):297-306
We use a set of Stäckel potentials to obtain a local approximation for an effective third integral in axisymmetric systems. We present a study on the feasibility and effectiveness of this approach. We apply it to three trial potentials of various flattenings, corresponding to nearly ellipsoidal, discy and boxy density isophotes. In all three cases, a good fit to the potential requires only a small set of Stäckel potentials, and the associated Stäckel third integral provides a very satisfactory, yet analytically simple, approximation to the trial potentials effective third integral. 相似文献
94.
George J. Bendo Joshua E. Barnes 《Monthly notices of the Royal Astronomical Society》2000,316(2):315-325
We use Gauss–Hermite functions to study the line-of-sight velocity distributions in simulated merger remnants. Our sample contains 16 remnants; eight produced by mergers between disc galaxies of equal mass, and eight produced by mergers between disc galaxies with mass ratios of 3:1. The equal-mass mergers display a wide range of kinematic features, including counterrotation at large radii, orthogonally rotating cores and misaligned rotational axes. Most of the unequal-mass remnants exhibit fairly regular disc-like kinematics, although two have kinematics more typical of the equal-mass remnants. Our results may be compared with observations of early-type objects, including ellipticals with misaligned kinematic axes, counterrotating systems and S0 galaxies. 相似文献
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R. Capuzzo-Dolcetta A. Vicari 《Monthly notices of the Royal Astronomical Society》2005,356(3):899-912
The present work extends and deepens previous examinations of the evolution of globular cluster orbits in elliptical galaxies, by means of numerical integrations of a wide set of orbits in five self-consistent triaxial galactic models characterized by a central core and different axial ratios. These models are valid and complete in the representation of regular orbits in elliptical galaxies. Dynamical friction is definitely shown to be an efficient cause of evolution for the globular cluster systems in elliptical galaxies of any mass or axial ratio. Moreover, our statistically significant sample of computed orbits confirms that the globular cluster orbital decay times are, at least for clusters moving on box orbits, much shorter than the age of the galaxies. Consequently, the mass carried into the innermost galactic region in the form of decayed globular clusters may have contributed significantly to feeding and accreting a compact object therein. 相似文献
97.
我们从四个方面综述星系闭的射电研究进展。首先介绍了星系闭中的分立射电源，特别是ｃＤ星系研究的一些最新进展和结果。继而介绍了星系闭中射电晕的分类、目前的观测结果和理论解释。星闭中的磁场主要由射电研究得出，在本文中对此也作了适当的介绍和讨论。最后还简介了在星系闭射观测中发现的ｒｅｌｉｃ射电源。 相似文献
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Ignacio Trujillo † C. J. Conselice Kevin Bundy M. C. Cooper P. Eisenhardt Richard S. Ellis 《Monthly notices of the Royal Astronomical Society》2007,382(1):109-120
Using the combined capabilities of the large near-infrared Palomar/DEEP-2 survey, and the superb resolution of the Advanced Camera for Surveys HST camera, we explore the size evolution of 831 very massive galaxies ( M ⋆ ≥ 1011 h −2 70 M⊙ ) since z ∼ 2 . We split our sample according to their light concentration using the Sérsic index n . At a given stellar mass, both low ( n < 2.5) and high ( n > 2.5) concentrated objects were much smaller in the past than their local massive counterparts. This evolution is particularly strong for the highly concentrated (spheroid like) objects. At z ∼ 1.5 , massive spheroid-like objects were a factor of 4 (±0.4) smaller (i.e. almost two orders of magnitudes denser) than those we see today. These small sized, high-mass galaxies do not exist in the nearby Universe, suggesting that this population merged with other galaxies over several billion years to form the largest galaxies we see today. 相似文献
100.