Evidence for a positive cosmological constant from flows of galaxies and distant supernovae
Article Abstract:
It has been possible to derive an independent constrain on the lower limit to the mass density of the universe, based on deviations of galaxy velocities from a smooth universal expansion. This constraint seems to indicate an almost flat universe in which there are comparable contributions from mass density and the cosmological constant. The favoured model is an unrestricted universe that will accelerate indefinitely. It is not yet possible to ascertain whether the global geometry is flat, open or closed.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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Cosmological baryon density derived from the deuterium abundance at redshift z = 3.57
Article Abstract:
The primordial ratio of deuterium to hydrogen nuclei (D/H) of 2.3 X 10 to -5th power measured in a high-redshift absorption system is similar to that in the interstellar medium. The ratio gives an accurate estimate of the cosmological density of baryons. The method of determining the ratio eliminates strong contamination in the absorption spectra, which is common in other methods. The optical spectra of a quasar at red shift z = 3.78 are used in the study.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Abundance of 3He in the local interstellar cloud
Article Abstract:
The sum of deuterium and 3He abundances in the local interstellar cloud has remained the same since the formation of the Solar System. A study analyzes the isotopes of helium atoms in the Solar System. The helium originates from the surrounding interstellar medium. The primordial abundances of different elements provide important information about the nucleosynthetic processes that occurred during the Big Bang.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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