Casuso, E.; Beckman, J. E.
Bibliographical reference
The Astronomical Journal, Volume 118, Issue 5, pp. 1907-1911.
Advertised on:
11
1999
Citations
6
Refereed citations
4
Description
This article presents a theoretical framework for the evolution of the
light-element nuclides in the Galactic disk. By understanding this
evolution correctly, we can reliably obtain the primordial abundances of
the nuclides D, 4He, and 7Li. We use two key
assumptions, those of (1) infall of metal-poor gas to the disk at an
increasing rate and (2) destruction, as well as production (except for
D), of fragile nuclides in hot, relatively dense supergiant envelopes.
Light nuclides are accelerated by supernova shocks, and many are
confined to hot interstellar zones by magnetic fields. Their repeated
passage through the hot envelopes causes depletion, which peaked during
the main star-forming phase of Galaxy evolution around z~1, as measured
from the Hubble Deep Field. This mechanism has dominated stellar
depletion in reducing the D/H abundance from its primordial value of
~=2x10-4 to its solar system value of ~=2.5x10-5
and subsequently to the current interstellar medium value of
1.5x10-5. The model accounts well for the solar system and
the current ratios of 7Li/6Li and
11B/10B. It fits extremely well a standard big
bang nucleosynthesis model with baryon density ~=0.05.