Neutron Stars
Mostrando 1-12 de 17 artigos, teses e dissertações.
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1. An Overview of Research into Low Internal Friction Optical Coatings by the Gravitational Wave Detection Community
The direct detection of gravitational waves by ground-based interferometric gravitational wave detectors in recent years has opened a new window of the universe, allowing the astrophysical observations of previously unexplored phenomena, such as the collisions of black holes and neutron stars. However, small thermodynamic fluctuations of the density of the t
Mat. Res.. Publicado em: 24/05/2018
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2. Different approaches to the Composition of Neutron Stars and their Environment / Diferentes abordagens à composição e ao ambiente das estrelas de nêutrons
Even after 80 years of intense research, the composition of neutron stars remains unknown, since both the dense matter in the interior of these compact objects and the matter moving around them are in extreme physical conditions, unreproducible in terrestrial laboratories. In this Thesis, we follow four different interconnected ways to approach these extreme
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 12/04/2012
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3. Núcleos exóticos e síntese dos elementos químicos
We have around ninety chemical elements available in nature, which were produced mainly by nuclear reactions inside stars. The fusion reactions are the main synthesis process which generates the light and intermediate masses elements. The synthesis begins with the hydrogen burning reaching the region of iron mass nuclei. Heavier elements are synthesized by n
Química Nova. Publicado em: 2012
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4. Formação de ressonâncias delta em estrelas de nêutron com a mudança das constantes de acoplamento híperon-méson / Formation of delta resonances in neutron stars with changing of the hyperon-meson coupling constants
No presente trabalho investigamos os efeitos da mudança das constantes de acoplamento entre os híperons (D; L; S e X) e os mésons (s; w e r) tendo em vista sua aplicacação na estrutura de estrelas de nêutron. Para tanto, adotamos o modelo de Walecka não-linear numa aproximacão de campo médio.
Publicado em: 2011
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5. Transições de fase hádron-quark em estrelas de nêutrons
Recent advances on the field of high energy physics have enabled the study of matter under extreme conditions and, in this context, new states of matter are being discovered and speculated upon. Among these hypothetical states of matter is the one of deconfined quarks in high densities and/or temperatures. An environment with extreme densities and low temper
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2011
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6. Adiabatic index of hot and cold compact objects
In the present work we calculate the adiabatic index of neutron stars formed by hadronic or quarkionic matter, under two possible conditions, with and without trapped neutrinos, and for two values of the entropy per baryon S = 0,2 kB/ baryon. We use the nonlinear Walecka model to describe hadronic stars, and the MIT bag model to describe quark stars. Particl
Brazilian Journal of Physics. Publicado em: 2010-06
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7. Estudo de população de estrelas de nêutrons isoladas emissoras de raios X e silenciosas em rádio / Population study of radio-quiet and thermally emitting isolated neutron stars
O objetivo da tese é estudar as propriedades da população Galáctica de estrelas de nêutrons isoladas com emissão térmica em raios X mas silenciosas em rádio. Isto é feito iinvestigando-se a amostra existente de sete fontes próximas, conhecidas como Magnificent Seven (M7), assim como através da procura por novos candidatos e restringindo possíveis
Publicado em: 2009
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8. Quark matter (strangelets) from astrophysical sources and its detection by terrestrial experiments. / Matéria de quarks (strangelets) de origem astrofísica e sua detecção por experimentos terrestres
The strange quark matter hypothesis, which states that a plasma composed of quarks up, down and strange in roughly equal amounts is absolutely stable at zero pressure, has been studied for more than twenty years, both theoretically and during searches for its detection in specific experiments. If strange quark matter is indeed stable, then there could be imp
Publicado em: 2008
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9. Cold and dense perturbative Yukawa theory with massive fermions
Recent results for the two-loop thermodynamic potential of QCD at finite density have shown that nonzero quark mass corrections to the pressure are relevant and can dramatically affect the structure of compact stars. Motivated by these findings, we consider a simple toy model - cold and dense Yukawa theory - to study the effects of finite fermion masses on t
Brazilian Journal of Physics. Publicado em: 2007-03
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10. Padrões de abundâncias entre estrelas muito pobres em metais no halo da galáxia / Abundance patterns among very metal-poor stars in the halo of the Galaxy: a statistical approach
Um dos maiores desafios da Astrofísica é tentar compreender a complexidade da composição química das estrelas. Elementos com massas atômicas acima de A>60 são formados pelos chamados processos de captura de nêutrons (processo-s e processo-r). A presença destes em espectros de estrelas de baixa massa (longo período de vida) e com pouco conteúdo met
Publicado em: 2007
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11. Compact Stars and Black Holes - A Comparative Study of Physical Properties and Quasi-Normal Modes / "Estrelas compactas e buracos negros - um estudo comparativo de propriedades físicas e de modos quasi-normais"
Este trabalho visa o estudo das perturbações de sistemas gravitacionais altamente compactos, como buracos negros e estrelas de nêutrons e de quarks. As perturbações em questão podem ser de diversas naturezas (escalar, eletromagnética ou gravitacional), sendo que detivemo-nos mais atentamente naquelas de natureza gravitacional, pois estas têm desperta
Publicado em: 2006
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12. The importance of strange mesons in neutron star properties
In order to obtain the properties of compact stellar objects, appropriate equations of state have to be used. In the literature, strange meson fields, namely the scalar meson field sigma*(975) and the vector meson field phi(1020), had to be considered in order to reproduce the observed strongly attractive LL interaction. The introduc
Brazilian Journal of Physics. Publicado em: 2005-09