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Title: Experimental measurements of the 15O(alpha,gamma)19Ne reaction rate and the stability of thermonuclear burning on accreting neutron stars

Abstract

Neutron stars in close binary star systems often accrete matter from their companion stars. Thermonuclear ignition of the accreted material in the atmosphere of the neutron star leads to a thermonuclear explosion which is observed as an X-ray burst occurring periodically between hours and days depending on the accretion rate. The ignition conditions are characterized by a sensitive interplay between the accretion rate of the fuel supply and its depletion rate by nuclear burning in the hot CNO cycle and the rp-process. For accretion rates close to stable burning the burst ignition therefore depends critically on the hot CNO breakout reaction {sup 15}O({alpha}, {gamma}){sup 19}Ne that regulates the flow between the hot CNO cycle and the rapid proton capture process. Until recently, the {sup 15}O({alpha}, {gamma}){sup 19}Ne reaction rate was not known experimentally and the theoretical estimates carried significant uncertainties. In this paper we perform a parameter study of the uncertainty of this reaction rate and determine the astrophysical consequences of the first measurement of this reaction rate. Our results corroborate earlier predictions and show that theoretically burning remains unstable up to accretion rates near the Eddington limit, in contrast to astronomical observations.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
919621
Report Number(s):
UCRL-JRNL-230876
Journal ID: ISSN 0004-637X; ASJOAB; TRN: US0806459
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, vol. 665, n/a, August 10, 2007, pp. 637; Journal Volume: 665
Country of Publication:
United States
Language:
English
Subject:
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BINARY STARS; CNO CYCLE; IGNITION; NEUTRON STARS; PROTONS; STABILITY; STARS; THERMONUCLEAR EXPLOSIONS; THERMONUCLEAR IGNITION

Citation Formats

Fisker, J, Tan, W, Goerres, J, Wiescher, M, and Cooper, R. Experimental measurements of the 15O(alpha,gamma)19Ne reaction rate and the stability of thermonuclear burning on accreting neutron stars. United States: N. p., 2007. Web.
Fisker, J, Tan, W, Goerres, J, Wiescher, M, & Cooper, R. Experimental measurements of the 15O(alpha,gamma)19Ne reaction rate and the stability of thermonuclear burning on accreting neutron stars. United States.
Fisker, J, Tan, W, Goerres, J, Wiescher, M, and Cooper, R. Tue . "Experimental measurements of the 15O(alpha,gamma)19Ne reaction rate and the stability of thermonuclear burning on accreting neutron stars". United States. doi:. https://www.osti.gov/servlets/purl/919621.
@article{osti_919621,
title = {Experimental measurements of the 15O(alpha,gamma)19Ne reaction rate and the stability of thermonuclear burning on accreting neutron stars},
author = {Fisker, J and Tan, W and Goerres, J and Wiescher, M and Cooper, R},
abstractNote = {Neutron stars in close binary star systems often accrete matter from their companion stars. Thermonuclear ignition of the accreted material in the atmosphere of the neutron star leads to a thermonuclear explosion which is observed as an X-ray burst occurring periodically between hours and days depending on the accretion rate. The ignition conditions are characterized by a sensitive interplay between the accretion rate of the fuel supply and its depletion rate by nuclear burning in the hot CNO cycle and the rp-process. For accretion rates close to stable burning the burst ignition therefore depends critically on the hot CNO breakout reaction {sup 15}O({alpha}, {gamma}){sup 19}Ne that regulates the flow between the hot CNO cycle and the rapid proton capture process. Until recently, the {sup 15}O({alpha}, {gamma}){sup 19}Ne reaction rate was not known experimentally and the theoretical estimates carried significant uncertainties. In this paper we perform a parameter study of the uncertainty of this reaction rate and determine the astrophysical consequences of the first measurement of this reaction rate. Our results corroborate earlier predictions and show that theoretically burning remains unstable up to accretion rates near the Eddington limit, in contrast to astronomical observations.},
doi = {},
journal = {Astrophysical Journal, vol. 665, n/a, August 10, 2007, pp. 637},
number = ,
volume = 665,
place = {United States},
year = {Tue May 08 00:00:00 EDT 2007},
month = {Tue May 08 00:00:00 EDT 2007}
}