Universe chemical evolution

Calvin M. Chemical Evolution. Oxford University Press. 

Holland HD (1984) The Chemical Evolution of the Atmosphere and Oceans. Princeton University Press, Princeton, NI loyce GF (1989) Nature 338 217... 

Bakasov A, Ha T-K, Quack M (1995) Ab initio Calculation of molecular energies including parity violating interactions. In Chela-Flores J, Raulin F (eds) Chemical Evolution Physics of the Origin of Life. Kluwer, Dordrecht Boston London, p 287 Ball P (1994) Designing the Molecular World, Chemistry at the Frontier, Princeton University... 

Massive stars play an important role in numerous astrophysical contexts that range from the understanding of starburst environments to the chemical evolution in the early Universe. It is therefore crucial that their evolution be fully and consistently understood. A variety of observations of hot stars reveal discrepancies with the standard evolutionary models (see [1] for review) He and N excesses have been observed in O and B main sequence stars and large depletions of B accompanied by N enhancements are seen in B stars and A-F supergiants [2,3,4,5], All of these suggest the presence of excess-mixing, and have led to the development of a new generation of evolutionary models which incorporate rotation (full reviews in [1], [6], [7]). 

Although Ba and heavier elements seem to fit the solar r-process pattern, lighter elements show wide varieties [5]. In particular, a large dispersion has been found in [Sr/Ba] at low metallicity[l], suggesting that lighter elements such as Sr does not come from a universal process, which produces Ba and Eu, but from weak r-process. An inhomogeneous chemical evolution model suggests that the dispersions in [Sr/Ba] are well-explained, when weak r-process produces 60% of Sr but only 1% of Ba in metal-poor stars. Furthermore, intermediate mass elements such as Pd must provide clues to understand the weak r-process yield. 

University of Maryland, Laboratory of Chemical Evolution, College Park, MD 20742... 

Holland HD (1984) The chemical evolution of the atmosphere and oceans. Princeton University... 

Calvin, M. Chemical Evolution Oxford University Press Oxford, U.K., 1969. 

Clayton DD (1988) Stellar nucleosynthesis and chemical evolution of the solar neighborhood. In Meteorites and the Early Solar System. Kerridge JF, Matthews MS (eds) University of Arizona Press, Tucson, p 1021-1062... 

Following this new Copemican revolution, far from being horrified by the remoteness of the stars and by the tremendous divergence operating across the whole Universe, astronomers set abont drawing up an overview of the new paradigm and determining its structural and chemical evolution. 

The VLT, centrepiece of the ESO, promises an exceptional harvest of astronomical data. Understanding the chemical evolution of the Universe requires a coordinated study of the most remote objects, ancient stars in the galactic halo and absorbent clouds in the line of sight of quasars. To this end, the high-resolution spectrograph UVES (Ultraviolet Echelle Spectrograph) was set at one focus of Kueyen, one of the four components of the VLT, perched at the top... 

Star, driving force behind the chemical evolution of the galaxies, mother of atoms and of all life, gentle or explosive, let us seek to become better acquainted. Eor it is one thing to observe and record the state of atomic matter in the Universe, and quite another to explain it. It is to this Herculean task that nuclear astrophysics dedicates it best troops. And the starting-point for each sally is the Sun, our personal reference. 

By studying the X-ray line of iron at 6.7 keV, we will greatly improve our understanding of the progressive synthesis of metals, and more generally, the chemical evolution of the cosmos. The composition, mass and temperature of the true intergalactic medium, which seems to be dominated by a very hot gas with filamentary structure, should also be revealed by XEUS, a marvellous balcony looking out across the Universe. May we relish the prospect ... 

Zinc has thus been promoted to the rank of prime evolutionary indicator for galaxies or protogalaxies associated with DLA absorbers. With its help, we aim to measure the chemical evolution of the Universe, because it leaves its signature on the spectra of the most distant objects and because it is predisposed to the gaseous state (Fig. 8.9). 

Pagel B.E.J. (1997) Nucleosynthesis and Chemical Evolution of Galaxies (Cambridge University Press, Cambridge). 

Mason, S. F., Chemical Evolution. Oxford University, New York, 1991. 

Nomoto, K., Hashimoto, M. 1987, in Chemical Evolution of Galaxies with Active Star Formation, ed. K. Takakubo., Universal Acad. Press, p. 93. 

Viola, V. E. LiBeB Nucleosynthesis and Clues to the Chemical Evolution of the Universe, in O. Manuel, Ed., Origin of Elements in the Solar System Implications of Post-1957 Observations, Kluwer, New York, 2000. 

The molecules found to date are composed of the elements H, C, N, O, Si, S, and Cl with the bulk of the molecules containing H, C, N, and O. The light elements H, D, and He are of cosmological origin and are therefore tracers of the early universe. On the other hand the heavier elements C, N, O,... are produced in stars by the processes of stellar nucleosynthesis. In addition to the most abundant isotopic forms many stable isotopes such as D, 13C, 170, lsO, 15N, 30Si, 33S, and 34S have been detected (see Appendix 1). The detailed determination of isotopic ratios — though often beset with formidable difficulties — has become a useful indicator of the chemical evolution of molecular clouds and the past chemical history of the galaxy. 

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