Other
Scientific paper
Dec 1992
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992aas...18110703w&link_type=abstract
American Astronomical Society, 181st AAS Meeting, #107.03; Bulletin of the American Astronomical Society, Vol. 24, p.1292
Other
Scientific paper
If material initially in nuclear statistical equilibrium (NSE) at high temperature and containing a large fraction of alpha -particles (or nucleons) is expanded and cooled so rapidly that not all the alpha -particles have time to reassemble, its final composition will differ substantially from what is traditionally calculated for particle-deficient freeze-outs. It has long been known that this phenomenon, the ``alpha -rich freeze-out," can lead to the production of elements heavier than the iron group, but only up to about zinc (A ~ 66). Here we explore the alpha -rich freeze-out for values of neutron excess larger than previously treated and discover nuclear systematics that, for neutron excesses greater than about 0.05, allow the creation of heavier elements all the way up to A ~ 100, even when most of the ejecta is in the form of heavy elements. In the limit of a very large fraction of unassembled alpha -particles and a large neutron excess, the alpha -rich freeze-out merges smoothly into the classical r-process. In contrast to previous studies, we find that a large part of the nuclear flow in the r-process may be carried by charged particle reactions up to about A = 100. We speculate that the site of these processes is the high entropy ``wind'' of a young (age 1-10 s) neutron star in which neutrino energy deposition is driving mass loss. The appropriate conditions exist in the delayed supernova explosion mechanism of Mayle & Wilson, but they may occur in other models as well. The mass of r-process ejected per supernova is expected to be ~ 10(-4) M\sun \ per Type II or Type Ib supernova, but this will be sensitive to details of the presupernova structure, the explosion mechanism, and the amount of material that falls back onto the neutron star when the reverse shock arrives there.
Hoffman Robert D.
Woosley Stan E.
No associations
LandOfFree
The alpha -Process and the r-Process does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The alpha -Process and the r-Process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The alpha -Process and the r-Process will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1112102