搜索结果: 1-15 共查到“知识库 天体化学”相关记录60条 . 查询时间(1.748 秒)
Preface: Evolution of the solar system: New advances in cosmochemistry and planetary chemistry
cosmochemistry planetary chemistry
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2017/4/10
The understanding of evolution of solar system has been
recently entered a phase of major change with the results
of new astronomical observation, several primitive extraterrestrial
samples includi...
Distribution and supply mechanisms of high uranium concentration in the rivers of Okinawa Island, Japan
uranium river Okinawa Island guideline value supply mechanism
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2017/4/10
Uranium concentrations in the rivers of Okinawa Island, Japan were determined in this study. Most rivers in the
southwestern area of the island showed high U concentrations, the highest of which was ...
中性氢研究的前沿问题
星际介质 中性氢 结构
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2012/9/12
氢元素是宇宙中重子物质的一种主要成分。处于中性状态的原子氢(通常简称为中性氢)在宇宙中分布广泛,是恒星和星系的物质基础。中性氢是分子云中的一种重要成分。它在星系中的分布广泛而延展,是研究星系的物质分布、动力学以及暗物质性质很好的示踪物。中性氢的研究已经有较长的历史,随着射电望远镜灵敏度和角分辨率的提高,正在形成越来越多对中性氢的新认识。对中性氢的进一步研究对其他一些天体物理研究也有重要意义。概括中...
快中子俘获过程（r过程）可以解释大约一半比铁重的稳定（和一些长寿命放射性的）富中子核素的产生，这已经被太阳系及各种金属丰度下恒星的观测结果所证实。为建立r过程模型，需要大量的核物理信息：涉及到β稳定谷与中子滴线之间的各种核素的稳定特性及口衰变分支等物理参数，实验和理论都面临巨大的挑战。综述了近年来贫金属星r过程核合成理论的研究情况，包括人们比较关注的主要C过程与弱r过程核合成、元素丰度分布规律及其...
The Chemical Evolution of Narrow Emission Line Galaxies: the Key to their Formation Processes
galaxy: activity galaxy: formation galaxy: chemical evolution
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2011/10/20
Using the largest sample of narrow emission line galaxies available so far, we show that their spectral characteristics are correlated with different physical parameters, like the chemical abundances,...
Collapse thresholds for the formation of CDM haloes in the ellipsoidal collapse model
cosmology: dark matter – methods: numerical
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2011/10/20
In the excursion set approach to structure formation initially spherical regions of the linear density field collapse if the average density contrast within them exceeds some critical value, \delta_c....
Detailed Chemical Abundances of Four Stars in the Unusual Globular Cluster, Palomar 1
Detailed Chemical Abundance Unusual Globular Cluster Palomar
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2011/10/17
Detailed chemical abundances for twenty one elements are presented for four red giants in the anomalous outer halo globular cluster Palomar 1 ($R_{\rm{GC}} = 17.2$ kpc, $Z=3.6$ kpc) using high-resolut...
Formation and Evolution of the Dust in Galaxies. II. The Solar Neighbourhood
Galaxies - Dust Galaxies – Spirals Galaxies – Milky Way
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2011/10/13
Over the past decade a new generation of chemical models have included the dust in the treatment of the ISM. This major accomplishment has been spurred by the growing amounts of data on the highly obs...
Isotropic extensions of the vacuum solutions in general relativity
Isotropic extensions of the vacuum solutions in general relativity
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2011/10/17
In this work we obtain isotropic extensions of the usual spherically symmetric vacuum geometries in general relativity. Exact and perturbative solutions are derived. The classes of geometries obtained...
A Chemical Abundance Study of 10 Open Clusters Based on WIYN-Hydra Spectroscopy
Chemical Abundance Study Clusters Based WIYN-Hydra Spectroscopy
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2011/10/12
We present a detailed chemical abundance study of evolved stars in 10 open clusters based on Hydra multi-object echelle spectra obtained with the WIYN 3.5m telescope. From an analysis of both equivale...
CNO and F abundances in the barium star HD 123396
stars: individual (HD123396: HIP 69834) – stars: abundances – stars: atmospheres – stars: barium
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2011/10/10
Barium stars are moderately rare, chemically peculiar objects, which are believed to be the result of the pollution of an otherwise normal star by material from an evolved companion on the asymptotic ...
Broad Line Radio Galaxies Observed with Fermi-LAT: The Origin of the GeV Gamma-Ray Emission
Broad Line Radio Galaxies Fermi-LAT:OriginGeV Gamma-Ray Emission
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2011/10/10
We report on a detailed investigation of the gamma-ray emission from 18 broad line radio galaxies (BLRGs) based on two years of Fermi Large Area Telescope (LAT) data. We confirm the previously reporte...
Effects of dust on light-curves of εAur type stars
Accretion, accretion disks – Scattering – binaries: eclipsing – circumstellar matter – Stars: individual: ǫ Aur
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2011/10/11
\epsilon Auriga is one of the most mysterious objects on the sky. Prior modeling of its light-curve assumed a dark, inclined, non-transparent or semi-transparent, dusty disk with a central hole. The h...
The Chemistry of the Early Universe
stars: formation – galaxies: formation – cosmology: theory
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2011/10/10
The chemistry of the early Universe is a fascinating field of study. Even in the absence of any elements heavier than lithium, a surprising degree of chemical complexity proves to be possible, giving ...
Chemistry in a gravitationally unstable protoplanetary disc
stars: pre-main-sequence, stars: circumstellar matter, protoplanetary discs, astrochemistry
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2011/10/9
Until now, axisymmetric, alpha-disc models have been adopted for calculations of the chemical composition of protoplanetary discs. While this approach is reasonable for many discs, it is not appropria...