Mechanism of thermonuclear burning propagation in a helium layer on a neutron star surface: A refined model with heat conduction and subgrid turbulence

• Published in: Astronomy letters Vol. 38; no. 5; pp. 305 - 320
• Main Authors: Simonenko, V. A., Gryaznykh, D. A., Litvinenko, I. A., Lykov, V. A., Shushlebin, A. N.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01-05-2012; Pleiades; Springer Nature B.V
• Subjects: Astronomy; Astrophysics; Astrophysics and Astroparticles; Fluid mechanics; Free surfaces; Helium; Numerical analysis; Observations and Techniques; Physics; Physics and Astronomy; Propagation; Stars & galaxies; numerical simulations; thermonuclear burning; X-ray bursts
• ISSN: 1063-7737; 1562-6873
• DOI: 10.1134/S1063773712050088

Results of 2D numerical simulations of thermonuclear burning propagation in a helium layer on a neutron star surface using the Euler-Lagrange TIGR-3T code are presented. This process is crucial for the development of type I X-ray bursts. Ignition and thermonuclear burning propagation are fairly easy to obtain when simulating a layer with a density at the bottom of 1.75 × 10
8
g cm
−3
. Such a simulation allows it to be compared with previous simulations based on other codes, including the simulation based on the MPM code described previously. However, this density is two orders of magnitude higher than can be obtained in observed bursters. The implementation of efficient numerical methods for the description of heat conduction and turbulence in the TIGR-3T code has allowed simulations to be performed for a layer with a density at the bottom of 1.8 × 10
7
g cm
−3
. The fulfilment of certain conditions on the size and shape of the initial temperature perturbation is required for the propagation of thermonuclear burning. Simulations reveal a peculiar burning propagation mechanism through compression of the layer ahead of the burning front by the matter transferred above the free surface.