Results 251 to 260 of about 60,296 (295)

Chemical Evolution of the Galaxy

Annual Review of Astronomy and Astrophysics, 1991
Since the discovery of the cosmic microwave background ( 1 84), it is gen­ erally assumed that the universe originated from a hot big bang (78). Detailed nucleosynthesis calculations based on the hot big bang model (e.g. 4, 1 82, 221 ) showed that no element heavier than 9Be could have been synthesized primordially with an abundance exceeding 101 4 by ...
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Chemical Evolution of Galaxies

1987
We review some of the present ideas on chemical evolution of irregular galaxies and disks of spiral galaxies. Based on the O abundances in stars and H II regions we present a discussion of the yield; we also discuss the effects of large scale mass flows and of cold dark matter to explain variations in the observed yield. The C, N, O observed abundances
S. Torres-Peimbert, M. Peimbert
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The Chemical Evolution of Galaxies

Progress in Particle and Nuclear Physics, 1986
After a brief introduction into the evolution of spiral galaxies, the observational evidence for temporal and spatial abundance variations across the galactic disk is discussed. The theoretical framework of chemical evolution models is summarised, followed by a critical discussion of available constraints. Solutions applying to the special cases of the
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The Chemical Evolution of Dwarf Galaxies

Astrophysics and Space Science, 2001
Various observations of dwarf starburst galaxies have revealed homogeneous abundance within the ionized region suggesting that the measured metallicities do not result from the metals ejected during the current burst (because they should not have time to mix homogeneously at such large scale) but from previous star formation episodes.
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Chemical evolution of the galaxy

AIP Conference Proceedings, 1995
The article presents data on and discussion of various issues related to element abundance trends in our Galaxy as a function of metallicity [Fe/H]: halo star abundances, evolution of the Galactic supernova rates, the age‐metallicity relationship for disk stars, and halo and disk star formation history and nycleosynthesis timescales. (AIP)
J. W. Truran, F. X. Timmes
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Chemical Evidence for Evolution of Galaxies

Astrophysics and Space Science, 2001
I have compiled the very best data published on abundance gradients. From this sample of 29 galaxies, some information can be gained on the mecanism of morphological evolution in disk galaxies. From this sample, I find that early-type galaxies show an identical trend in the behavior of extrapolated central abundance versus morphological type to that ...
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The chemical evolution of galaxies

Journal of Physics G: Nuclear and Particle Physics, 1993
The chemical evolution of galaxies is discussed starting with the simple box model. It is shown that this model with the additional assumption of metal-rich outflow provides a first useful insight into the chemical evolution of different stellar populations.
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Elliptical Galaxy Chemical Evolution

1999
Conclusions about elliptical and other early-type galaxies come from studies of integrated starlight and studies of giant stars in the nearest galaxies. The abundance distribution for all galaxy types at all radii appears to exhibit a “G dwarf problem” in that the distribution is more strongly peaked than the one-zone closed-box constantyield ...
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Chemical and Dynamical Evolution of Spiral Galaxies

Astrophysics and Space Science, 2002
We present the very first results of a new 3D numerical model for the formation and evolution of spiral galaxies along the Hubble sequence. We take into account the hydrodynamical properties of the gas with an SPH method while we use a tree code for the gravitational forces of the dark matter and stars.
Poirier, Sébastien, Jablonka, Pascale, Alimi, Jean-Michel   +2 more
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The chemical evolution of galaxies

Vistas in Astronomy, 1975
Abstract Emphasis is placed on the simplest models of the chemical evolution of galaxies, and the role played by the concentration of the interstellar gas to gravitational stable regions is taken into account. Although Schmidt's simple model is improved when concentration is allowed for, it still predicts too wide a spread of metal abundances for ...
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