Stars Abundances
Mostrando 1-8 de 8 artigos, teses e dissertações.
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1. Formação e evolução de galáxias: populações estelares na Via Láctea, galáxias elípticas e propriedades de galáxias em grupos / Galaxy Formation and Evolution: From the Milky Way to Galaxies in Groups
Understanding the way galaxies form and evolve throughout the cosmic time remains one of the greatest challenges of modern cosmology. Several processes are known to play a role in the formation of galaxies, such as feedback from supernovae and active galactic nuclei, chemical and dynamical evolution and environmental effects. This thesis encompasses these pr
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 13/03/2012
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2. Search for very metal-poor stars based on carbon over-abundance / Busca por estrelas muito pobres em metais baseada no enriquecimento em carbono
The main goal of this work is to show that is possible to search for metal-poor stars based on the premise that a large fraction of these will be carbon-rich. This hypothesis had not yet been verified because many of the so-called CEMP (Carbon Enhanced Metal-Poor) stars were neglected in previous studies due to the design of the search for metal-poor stars w
Publicado em: 2010
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3. Determination of chemical abundances in yellow symbiotic stars from the southern hemsiphere / "Determinação de abundâncias químicas em simbióticas amarelas austrais"
The present work is a contribution to the study of chemical composition of southern symbiotic stars, scarcely studied in literature. We present a complete set of yellow southern symbiotic stars extracted from Belczynski. Some of the objects analyzed had no spectroscopic data in literature. The data were obtained using 1.6m telescope in LNA, Brazil and the IU
Publicado em: 2004
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4. Sobre a relação entre rotação, atividade crosmosférica e abundância de lítio em estrelas subgigantes
The connection between rotation, CaII emission flux and lithium abundance is analyzed for a sample of subgiant stars, with evolutionary status was determined from the Toulouse-Geneve code and HlPPARCOS trigonometric parallax measurements. We noted that the distribution of rotation and CaII emission flux, as a function of effective temperature, shows a discon
Publicado em: 2003
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5. "Um Estudo Espectroscópico da Nova Velorum 1999 (V382 Vel)" / Spectral Evolution of Nova Velorum 1999 (V382 Vel)
O estudo da envoltória de novas clássicas permite diagnosticar com precisão aceitável as condições físicas nos estágios avançados do fenômeno de nova. A Nova Velorum 1999, foi a mais brilhante em 24 anos, sendo um ótimo caso para este estudo. Trata-se de uma nova de neônio, formada em um sistema onde se acredita que a primária seja uma anã bran
Publicado em: 2002
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6. International Ultraviolet Explorer satellite observations of seven high-excitation planetary nebulae
Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observed ionic con
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7. X-ray emission from clusters and groups of galaxies
Recent major advances in x-ray imaging and spectroscopy of clusters have allowed the determination of their mass and mass profile out to ≈1/2 the virial radius. In rich clusters, most of the baryonic mass is in the gas phase, and the ratio of mass in gas/stars varies by a factor of 2–4. The baryonic fractions vary by a factor of ≈3 from cluster to
National Academy of Sciences.
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8. Challenges to the standard model of Big Bang nucleosynthesis.
Big Bang nucleosynthesis provides a unique probe of the early evolution of the Universe and a crucial test of the consistency of the standard hot Big Bang cosmological model. Although the primordial abundances of 2H, 3He, 4He, and 7Li inferred from current observational data are in agreement with those predicted by Big Bang nucleosynthesis, recent analysis h