Abstract
view Abstract Citations (109) References (111) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galactic Evolution of D and 3He Galli, Daniele ; Palla, Francesco ; Ferrini, Federico ; Penco, Umberto Abstract The evolution of D and He-3 is considered in the framework of a consistent model for the chemical evolution of the Galaxy. The destruction of D in the course of galactic evolution is found to be modest, of the order of a factor of approximately 2; the good agreement found with the observed abundance of D in the presolar material and in the interstellar medium makes it possible to derive narrow constraints on the primordial D, or, equivalently, on the allowed range of the baryon-to-photon ratio eta according to standard big-bang nucleosynthesis. Conversely, the evolution of He-3 remains one of the major problems in the field of chemical galactic evolution: results based on the predictions of updated stellar models are shown to lead to an overproduction of He-3 by a factor of approximately 5-7 at the time of formation of the Sun, and by a factor of approximately 5-20 with respect to measured abundances in galactic H II regions. Several possibilities to reduce this discrepancy are presented and discussed quantitatively; none of them is found to produce the desired result, with the exception of a hypothetical low-energy resonance in the cross section of the He-3 (He-3, 2p) He-4 reaction, advocated also as a possible solution to the solar neutrino puzzle. Otherwise, the observed underabundance of He-3 in the presolar material and in H II regions must be considered as evidencing local inhomogeneities in the interstellar medium, in which He-3 is strongly depleted by some unknown process. Publication: The Astrophysical Journal Pub Date: April 1995 DOI: 10.1086/175546 Bibcode: 1995ApJ...443..536G Keywords: Abundance; Big Bang Cosmology; Chemical Evolution; Deuterium; Galactic Evolution; Helium Isotopes; Nuclear Fusion; Stellar Models; Baryons; H Ii Regions; Interstellar Matter; Novae; Photons; Solar Neutrinos; Astrophysics; ELEMENTARY PARTICLES; GALAXIES: EVOLUTION; NUCLEAR REACTIONS; NUCLEOSYNTHESIS; ABUNDANCES full text sources ADS | data products SIMBAD (2)
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