The cluster of galaxies LCDCS-S001: basic spectroscopic data and stellar population     

S. B. Rembold  M. G. Pastoriza 《Monthly notices of the Royal Astronomical Society》2007,374(3):1056-1066

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The magnetohydrodynamics of stellar structures     

G. S. Dubey  U. S. Pandey  J. P. Singh  L. K. Singh  S. N. Singh 《Journal of Astrophysics and Astronomy》1990,11(1):23-28

The equation governing the equilibrium of a centrally-symmetric, self-gravitating distribution of matter is obtained by assuming that matter is described by magnetofluid and it is shown that the equation of stellar structure described by an ideal fluid is recovered when magnetic fieldh is vanishing  相似文献   

原行星盘的研究进展     

刘尧  王红池 《天文学进展》2011,29(2):148-167

原行星盘是环绕在年轻星天体(如T Tauri型星,HAe/Be星)周围的气体尘埃盘,是具有初始角动量的分子云核在塌缩形成恒星过程中的自然结果,是行星系统的起源地。原行星盘研究不仅是恒星形成理论的重要组成部分,而且是行星形成理论的基础。首先介绍了盘的形成与演化规律;然后介绍了年轻星天体的能谱分布,盘的模型和参数(质量吸积率、质量、尺度、温度、寿命);随后讨论了尘埃颗粒在盘中生长的观测证据以及行星在盘中形成的大致过程;最后对原行星盘研究的现状和未来做了总结与展望。  相似文献   

Metallicity and kinematical clues to the formation of the Local Group     

R.F.G. Wyse 《Astronomische Nachrichten》2010,331(5):526-534

The kinematics and elemental abundances of resolved stars in the nearby Universe can be used to infer conditions at high redshift, trace how galaxies evolve and constrain the nature of dark matter. This approach is complementary to direct study of systems at high redshift, but I will show that analysis of individual stars allows one to break degeneracies, such as between star formation rate and stellar Initial Mass Function, that complicate the analysis of unresolved, distant galaxies (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Pulsations and planets: The asteroseismology‐extrasolar‐planet connection     

S. Schuh 《Astronomische Nachrichten》2010,331(5):489-501

The disciplines of asteroseismology and extrasolar planet science overlap methodically in the branch of high‐precision photometric time series observations. Light curves are, amongst others, useful to measure intrinsic stellar variability due to oscillations, as well as to discover and characterize those extrasolar planets that transit in front of their host stars, periodically causing shallow dips in the observed brightness. Both fields ultimately derive fundamental parameters of stellar and planetary objects, allowing to study for example the physics of various classes of pulsating stars, or the variety of planetary systems, in the overall context of stellar and planetary system formation and evolution. Both methods typically also require extensive spectroscopic follow‐up to fully explore the dynamic characteristics of the processes under investigation. In particularly interesting cases, a combination of observed pulsations and signatures of a planet allows to characterize a system's components to a very high degree of completeness by combining complementary information. The planning of the relevant space missions has consequently converged with respect to science cases, where at the outset there was primarily a coincidence in instrumentation and techniques. Whether space‐ or ground‐based, a specific type of stellar pulsations can themselves be used in an innovative way to search for extrasolar planets. Results from this additional method at the interface of stellar pulsation studies and exoplanet hunts in a beyond‐mainstream area are presented (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

The Hill stability of inclined small mass binary systems in three-body systems with special application to triple star systems, extrasolar planetary systems and Binary Kuiper Belt systems     

J.R. Donnison 《Planetary and Space Science》2010,58(10):1169-1179

The dynamical stability of a bound triple system composed of a small binary or minor planetary system moving on a orbit inclined to a central third body is discussed in terms of Hill stability for the full three-body problem. The situation arises in the determination of stability of triple star systems against disruption and component exchange and the determination of stability of extrasolar planetary systems and minor planetary systems against disruption, component exchange or capture. The Hill stability criterion is applied to triple star systems and extrasolar planetary systems, the Sun-Earth-Moon system and Kuiper Belt binary systems to determine the critical distances for stable orbits. It is found that increasing the inclination of the third body decreases the Hill regions of stability. Increasing the eccentricity of the binary also produces similar effects.These type of changes make exchange or disruption of the component masses more likely. Increasing the eccentricity of the binary orbit relative to the third body substantially decreases stability regions as the eccentricity reaches higher values. The Kuiper Belt binaries were found to be stable if they move on circular orbits. Taking into account the eccentricity, it is less clear that all the systems are stable.  相似文献   

Asteroseismic study of the red giant ε Ophiuchi     

Shao-Lan Bi  Ling-Huai Li  Yan-Ke Tang  Ning Gai 《天体物理学报》2010,(12):1265-1274

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Gaussian Modification of Neutrino Energy Losses in Electron Capture Processes of Nuclides Fe, Co, Ni and Mn in Stellar Interiors     

Jing-jing Liu  Zhi-quan Luo 《Chinese Astronomy and Astrophysics》2010,34(4):71

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Stellar Population Analysis of Galaxies based on Genetic Algorithms     

Abdel-Fattah Attia  H. A. Ismail  I. M. Selim  A. M. Osman  I. A. Isaa  M. A. Marie  A. A. Shaker 《中国天文和天体物理学报》2005,5(4):347-355

We present a new method for determining the age and relative contribution of different stellar populations in galaxies based on the genetic algorithm. We apply this method to the barred spiral galaxy NGC 3384, using CCD images in U, B, V, R and I bands. This analysis indicates that the galaxy NGC 3384 is mainly inhabited by old stellar population (age >109yr). Some problems were encountered when numerical simulations are used for determining the contribution of different stellar populations in the integrated color of a galaxy. The results show that the proposed genetic algorithm can search efficiently through the very large space of the possible ages.  相似文献   

Models of rapidly rotating neutron stars: remnants of accretion-induced collapse     

Yuk Tung Liu  Lee Lindblom 《Monthly notices of the Royal Astronomical Society》2001,324(4):1063-1073

Equilibrium models of differentially rotating nascent neutron stars are constructed, which represent the result of the accretion-induced collapse of rapidly rotating white dwarfs. The models are built in a two-step procedure: (1) a rapidly rotating pre-collapse white dwarf model is constructed; (2) a stationary axisymmetric neutron star having the same total mass and angular momentum distribution as the white dwarf is constructed. The resulting collapsed objects consist of a high-density central core of size roughly 20 km, surrounded by a massive accretion torus extending over 1000 km from the rotation axis. The ratio of the rotational kinetic energy to the gravitational potential energy of these neutron stars ranges from 0.13 to 0.26, suggesting that some of these objects may have a non-axisymmetric dynamical instability that could emit a significant amount of gravitational radiation.  相似文献