AbstractsAstronomy & Space Science

One-dimensional Turbulence Models of Type I X-ray Bursts

by Chen Hou

Institution: University of Minnesota
Year: 2016
Keywords: One-dimensional turbulence model; Photospheric radius expansion bursts; Type I X-ray bursts
Posted: 02/05/2017
Record ID: 2070138
Full text PDF: http://hdl.handle.net/11299/178958


Type I X-ray bursts are caused by thermonuclear explosions occurring on the surface of an accreting neutron star in a binary star system. Observations and simulations of these phenomena are of great importance for understanding the fundamental properties of neutron stars and dense matter because the equation of state for cold dense matter can be constrained by the mass-radius relationship of neutron stars. During the bursts, turbulence plays a key role in mixing the fuels and driving the unstable nuclear burning process. This dissertation presents one dimensional models of photospheric radius expansion bursts with a new approach to simulate turbulent advection. Compared with the traditional mixing length theory, the one-dimensional turbulence (ODT) model represents turbulent motions by a sequence of maps that are generated according to a stochastic process. The light curves I obtained with the ODT models are in good agreement with those of the KEPLER model in which the mixing length theory and various diffusive processes are applied. The abundance comparison, however, indicates that the differences in turbulent regions and turbulent diffusivities result in more 12{C} survival during the bursts in the ODT models, which can make a difference in the superbursts phenomena triggered by unstable carbon burning.