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Title: Fusion of neutron-rich oxygen isotopes in the crust of accreting neutron stars

Abstract

Fusion reactions in the crust of an accreting neutron star are an important source of heat, and the depth at which these reactions occur is important for determining the temperature profile of the star. Fusion reactions depend strongly on the nuclear charge Z. Nuclei with Z{<=}6 can fuse at low densities in a liquid ocean. However, nuclei with Z=8 or 10 may not burn until higher densities where the crust is solid and electron capture has made the nuclei neutron rich. We calculate the S factor for fusion reactions of neutron rich nuclei including {sup 24}O+{sup 24}O and {sup 28}Ne+{sup 28}Ne. We use a simple barrier penetration model. The S factor could be further enhanced by dynamical effects involving the neutron rich skin. This possible enhancement in S should be studied in the laboratory with neutron rich radioactive beams. We model the structure of the crust with molecular dynamics simulations. We find that the crust of accreting neutron stars may contain micro-crystals or regions of phase separation. Nevertheless, the screening factors that we determine for the enhancement of the rate of thermonuclear reactions are insensitive to these features. Finally, we calculate the rate of thermonuclear {sup 24}O+{sup 24}O fusion andmore » find that {sup 24}O should burn at densities near 10{sup 11} g/cm{sup 3}. The energy released from this and similar reactions may be important for the temperature profile of the star.« less

Authors:
; ;  [1]
  1. Department of Physics and Nuclear Theory Center, Indiana University, Bloomington, Indiana 47405 (United States)
Publication Date:
OSTI Identifier:
21189946
Resource Type:
Journal Article
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 77; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.77.045807; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2813
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ATOMIC NUMBER; BEAMS; CRYSTALS; DENSITY; ELECTRON CAPTURE; HEAT; LIQUIDS; MOLECULAR DYNAMICS METHOD; NEON 28; NEUTRON STARS; NEUTRON-RICH ISOTOPES; NEUTRONS; OXYGEN 24; SCREENING; SIMULATION; SOLIDS; THERMONUCLEAR REACTIONS

Citation Formats

Horowitz, C J, Dussan, H, Berry, D K, and University Information Technology Services, Indiana University, Bloomington, Indiana 47408. Fusion of neutron-rich oxygen isotopes in the crust of accreting neutron stars. United States: N. p., 2008. Web. doi:10.1103/PHYSREVC.77.045807.
Horowitz, C J, Dussan, H, Berry, D K, & University Information Technology Services, Indiana University, Bloomington, Indiana 47408. Fusion of neutron-rich oxygen isotopes in the crust of accreting neutron stars. United States. https://doi.org/10.1103/PHYSREVC.77.045807
Horowitz, C J, Dussan, H, Berry, D K, and University Information Technology Services, Indiana University, Bloomington, Indiana 47408. Tue . "Fusion of neutron-rich oxygen isotopes in the crust of accreting neutron stars". United States. https://doi.org/10.1103/PHYSREVC.77.045807.
@article{osti_21189946,
title = {Fusion of neutron-rich oxygen isotopes in the crust of accreting neutron stars},
author = {Horowitz, C J and Dussan, H and Berry, D K and University Information Technology Services, Indiana University, Bloomington, Indiana 47408},
abstractNote = {Fusion reactions in the crust of an accreting neutron star are an important source of heat, and the depth at which these reactions occur is important for determining the temperature profile of the star. Fusion reactions depend strongly on the nuclear charge Z. Nuclei with Z{<=}6 can fuse at low densities in a liquid ocean. However, nuclei with Z=8 or 10 may not burn until higher densities where the crust is solid and electron capture has made the nuclei neutron rich. We calculate the S factor for fusion reactions of neutron rich nuclei including {sup 24}O+{sup 24}O and {sup 28}Ne+{sup 28}Ne. We use a simple barrier penetration model. The S factor could be further enhanced by dynamical effects involving the neutron rich skin. This possible enhancement in S should be studied in the laboratory with neutron rich radioactive beams. We model the structure of the crust with molecular dynamics simulations. We find that the crust of accreting neutron stars may contain micro-crystals or regions of phase separation. Nevertheless, the screening factors that we determine for the enhancement of the rate of thermonuclear reactions are insensitive to these features. Finally, we calculate the rate of thermonuclear {sup 24}O+{sup 24}O fusion and find that {sup 24}O should burn at densities near 10{sup 11} g/cm{sup 3}. The energy released from this and similar reactions may be important for the temperature profile of the star.},
doi = {10.1103/PHYSREVC.77.045807},
url = {https://www.osti.gov/biblio/21189946}, journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 4,
volume = 77,
place = {United States},
year = {2008},
month = {4}
}