10 research outputs found
The reactions and ashes of thermonuclear explosions on neutron stars
This paper reports on the detailed rp-process reaction flow on an accreting
neutron star and the resulting ashes of a type I X-ray burst. It is obtained by
coupling a 298 isotope reaction network to a self-consistent one-dimensional
model calculation with a constant accretion rate of dM/dt=1.0e17g/s (0.09
Eddington).Comment: 4 pages, 2 figures, submitted to the INPC2004 proceeding
Extracting the rp-process from X-ray burst light curves
The light curves of type I X-ray bursts (XRBs) result from energy released
from the atmosphere of a neutron star when accreted hydrogen and helium ignite
and burn explosively via the rp-process. Since charged particle reaction rates
are both density and very temperature dependent, a simulation model must
provide accurate values of these variables to predict the reaction flow. This
paper uses a self-consistent one-dimensional model calculation with a constant
accretion rate of dM/dt=5e16g/s (0.045 Eddington) and reports on the detailed
rp-process reaction flow of a given burst.Comment: 4 pages, submitted to Nucl. Phys. A as part of the Nuclei in Cosmos 8
proceeding
Nuclear-reaction rates in the thermonuclear runaway phase of accreting neutron stars
The rp-process has been suggested as the dominant
nucleosynthesis process in explosive hydrogen burning at high
temperature and density conditions. The process is characterized by a
sequence of fast proton capture reactions and subsequent
-decays. The reaction path of the rp-process runs along the
drip line up to . Most of the charged-particle reaction
rates for the reaction path are presently based on statistical
Hauser-Feshbach calculations. While these rates are supposed to be reliable
within a factor of two for conditions of high density in the compound
nuclei, discrepancies may occur for nuclei near closed shells or near
the proton drip line where the -values of proton capture processes
are typically very small. It has been argued that the thermonuclear
runaway is less sensitive to the reaction rates because of the rapid
time-scale of the event. However, since these processes may operate
at the same time-scale as fast mixing and convection processes, a change
in reaction rates indeed may have a significant impact. In this paper we
present two examples, the break-out from the hot CNO cycles, and the
thermonuclear runaway in X-ray bursts itself, where changes in
reaction rates have a direct impact on time-scale, energy generation
and nucleosynthesis predictions for the explosive event