Galaxy Clusters
Mostrando 13-18 de 18 artigos, teses e dissertações.
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13. 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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14. The age of the universe from nuclear chronometers
An overview is presented of the current situation regarding radioactive dating of the matter of which our Galaxy is comprised. A firm lower bound on the age from nuclear chronometers of ≈9–10 Gyr is entirely consistent with age determinations from globular clusters and white dwarf cooling histories. The reasonable assumption of an approximately unif
National Academy of Sciences.
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15. The galaxy luminosity function and the redshift-distance controversy (A Review)
The mean relation between distance and redshift for galaxies is reviewed as an observational question. The luminosity function for galaxies is an important ingredient and is given explicitly. We discuss various observational selection effects that are important for comparison of the linear and quadratic distance-redshift laws. Several lines of evidence are r
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16. Globular clusters, Hipparcos, and the age of the galaxy
We discuss the impact of the results from the recent Hipparcos astrometric satellite on distance estimates of galactic globular clusters. Recalibrating the clusters not only implies a relatively small change in the distance to the Large Magellanic Cloud, and hence a rescaling of several estimates of the Hubble constant, but also leads to significantly y
National Academy of Sciences.
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17. 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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18. 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