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Title: Regimes of Helium Burning

Abstract

The burning regimes encountered by laminar deflagrations and Zeldovich von Neumann Doering [ZND] detonations propagating through helium-rich compositions in the presence of buoyancy-driven turbulence are analyzed. Particular attention is given to models of X-ray bursts that start with a thermonuclear runaway on the surface of a neutron star and to the thin-shell helium instability of intermediate-mass stars. In the X-ray burst case, turbulent deflagrations propagating in the lateral or radial direction encounter a transition from the distributed regime to the flamelet regime at a density of {approx}108 g cm-3. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than {approx}106 g cm-3. Self-sustained laminar deflagrations traveling in the radial direction cannot exist below this density. Similarly, the planar ZND detonation width becomes larger than the pressure scale height at {approx}107 g cm-3, suggesting that steady state, self-sustained detonations cannot come into existence in the radial direction. In the thin helium shell case, turbulent deflagrations traveling in the lateral or radial direction encounter the distributed regime at densities below {approx}107 g cm-3 and the flamelet regime at larger densities. In the radial direction, the purely laminar deflagration width is larger thanmore » the pressure scale height for densities smaller than {approx}104 g cm-3, indicating that steady state laminar deflagrations cannot form below this density. The planar ZND detonation width becomes larger than the pressure scale height at {approx}5x10{sup 4} g cm-3, suggesting that steady state, self-sustained detonations cannot come into existence in the radial direction. (c) 2000 The American Astronomical Society.« less

Authors:
;
Publication Date:
OSTI Identifier:
20217588
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 537; Journal Issue: 2; Other Information: PBD: 10 Jul 2000; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; HELIUM BURNING; DETONATION WAVES; NEUTRON STARS; STAR MODELS; FLOW MODELS; TURBULENCE; COSMIC X-RAY BURSTS; THEORETICAL DATA

Citation Formats

Timmes, F X, and Niemeyer, J C. Regimes of Helium Burning. United States: N. p., 2000. Web. doi:10.1086/309043.
Timmes, F X, & Niemeyer, J C. Regimes of Helium Burning. United States. https://doi.org/10.1086/309043
Timmes, F X, and Niemeyer, J C. Mon . "Regimes of Helium Burning". United States. https://doi.org/10.1086/309043.
@article{osti_20217588,
title = {Regimes of Helium Burning},
author = {Timmes, F X and Niemeyer, J C},
abstractNote = {The burning regimes encountered by laminar deflagrations and Zeldovich von Neumann Doering [ZND] detonations propagating through helium-rich compositions in the presence of buoyancy-driven turbulence are analyzed. Particular attention is given to models of X-ray bursts that start with a thermonuclear runaway on the surface of a neutron star and to the thin-shell helium instability of intermediate-mass stars. In the X-ray burst case, turbulent deflagrations propagating in the lateral or radial direction encounter a transition from the distributed regime to the flamelet regime at a density of {approx}108 g cm-3. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than {approx}106 g cm-3. Self-sustained laminar deflagrations traveling in the radial direction cannot exist below this density. Similarly, the planar ZND detonation width becomes larger than the pressure scale height at {approx}107 g cm-3, suggesting that steady state, self-sustained detonations cannot come into existence in the radial direction. In the thin helium shell case, turbulent deflagrations traveling in the lateral or radial direction encounter the distributed regime at densities below {approx}107 g cm-3 and the flamelet regime at larger densities. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than {approx}104 g cm-3, indicating that steady state laminar deflagrations cannot form below this density. The planar ZND detonation width becomes larger than the pressure scale height at {approx}5x10{sup 4} g cm-3, suggesting that steady state, self-sustained detonations cannot come into existence in the radial direction. (c) 2000 The American Astronomical Society.},
doi = {10.1086/309043},
url = {https://www.osti.gov/biblio/20217588}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 537,
place = {United States},
year = {2000},
month = {7}
}