Galaxy Formation
Mostrando 13-23 de 23 artigos, teses e dissertações.
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13. Cosmological implications of old galaxies at high redshifts
Old high-z galaxies are important tools for understanding the structure formation problem and may become the key to determine the ultimate fate of the Universe. In this paper, the inferred ages of the three oldest galaxies at high redshifts reported in the literature are used to constrain the first epoch of galaxy formation and to reanalyse the high-z time s
Brazilian Journal of Physics. Publicado em: 2001-12
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14. Determinação de parâmetros atmosféricos de estrelas em NGC 6528 e NGC 6553 - aglomerados globulares de referência para o estudo de populações ricas em metais / Derivation of atmospheric parameters of stars in NGC 6528 and NGC 6553 - globular clusters of reference for the study of metal-rich populations
The metal-rich bulge globular clusters are a keystone for the understanding of the evolutionary history of our Galaxy and the study of the bulge stellar populations provides constraints to models of bulge formation. In this work we present the study of 22 stars in the globular clusters NGC 6528 and NGC 6553, templates of the metal-rich populations of the bul
Publicado em: 2000
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15. Color Gradients and the Secular Evolutionary Scenario in Late-Type Spiral Galaxies / Gradientes de Cor e o Cenário de Evolução Secular em Galáxias Espirais de Tipo Tardio
Nós realizamos um estudo estatístico do comportamento de perfis de cor em bandas largas (UBV) para 257 galáxias espirais do tipo Sbc, ordinárias e barradas, utilizando dados obtidos através de fotometria fotoelétrica de abertura, disponíveis na literatura (Longo &de Vaucouleurs 1983,1985). Nós determinamos os gradientes de cor (B-V) e (U-B) para as g
Publicado em: 1999
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16. Dissipative processes in galaxy formation.
A galaxy commences its life in a diffuse gas cloud that evolves into a predominantly stellar aggregation. Considerable dissipation of gravitational binding energy occurs during this transition. I review here the dissipative processes that determine the critical scales of luminous galaxies and the generation of their morphology. The universal scaling relation
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17. The epoch of galaxy formation
The National Academy of Sciences of the USA.
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18. Galaxy formation
It is argued that within the standard Big Bang cosmological model the bulk of the mass of the luminous parts of the large galaxies likely had been assembled by redshift z ∼ 10. Galaxy assembly this early would be difficult to fit in the widely discussed adiabatic cold dark matter model for structure formation, but it could agree with an isocurvature v
National Academy of Sciences.
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19. Causes and effects of the first quasars.
The light we observe from the most distant known quasars set out when the Universe was about 200 times denser than it is now and less than one-tenth of its present age. The existence of these objects implies that galaxy formation had already, at that early epoch, proceeded to the stage when massive (>10(8)M[symbol, see text]) objects had accumulated in the c
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20. Galaxy dynamics and the mass density of the universe.
Dynamical evidence accumulated over the past 20 years has convinced astronomers that luminous matter in a spiral galaxy constitutes no more than 10% of the mass of a galaxy. An additional 90% is inferred by its gravitational effect on luminous material. Here I review recent observations concerning the distribution of luminous and nonluminous matter in the Mi
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21. Observing the epoch of galaxy formation
Significant observational progress in addressing the question of the origin and early evolution of galaxies has been made in the past few years, allowing for direct comparison of the epoch when most of the stars in the universe were forming to prevailing theoretical models. There is currently broad consistency between theoretical expectations and the ob
The National Academy of Sciences.
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22. Galaxies and large scale structure at high redshifts
It is now straightforward to assemble large samples of very high redshift (z ∼ 3) field galaxies selected by their pronounced spectral discontinuity at the rest frame Lyman limit of hydrogen (at 912 Å). This makes possible both statistical analyses of the properties of the galaxies and the first direct glimpse of the progression of the growth of the
National Academy of Sciences.
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23. Graviton scattering and matter distribution.
In this model gravitation results from the emission and absorption of quanta (gravitons) that are scattered a few times in crossing a typical galaxy. Many features of the universe can be explained in terms of this model, although theoretical justification for the scattering of gravitons is lacking. Gravitons follow a random walk and diffuse through the outer