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Recent work has proposed that a merger event between a red-giant and a He white dwarf may be responsible for the production of R-stars (Izzard et al, 2007). We investigate the proposed evolution and nucleosynthesis of such a model. We simulate the hypothesized late ignition of the core flash by increasing the neutrino losses until the ignition occurs sufficiently far from the centre that the subsequent evolution produces dredge-up of carbon to the extent that the post-flash object is a carbon star. Detailed nucleosynthesis is performed within this approximation, and we show that the overall properties are broadly consistent with the observations. Details will depend on the dynamics of the merger event.
Recent halo star abundance observations exhibit an important feature of consequence to the r-process: the presence of a main r-process between the second and third peaks which is consistent among halo stars. We explore fission cycling and steady-beta
In the context of f(R)=R + alpha R^2 gravity, we study the existence of neutron and quark stars with no intermediate approximations in the generalised system of Tolman-Oppenheimer-Volkov equations. Analysis shows that for positive alphas the scalar c
Previously we found that large amplitude $r$-modes could decay catastrophically due to nonlinear hydrodynamic effects. In this paper we found the particular coupling mechanism responsible for this catastrophic decay, and identified the fluid modes in
The astrophysical production site of the heaviest elements in the universe remains a mystery. Incorporating heavy element signatures of metal-poor, $r$-process enhanced stars into theoretical studies of $r$-process production can offer crucial constr
We report the discovery of J1521-3538, a bright (V=12.2), very metal-poor ([Fe/H]=-2.8) strongly r-process enhanced field horizontal branch star, based on a high-resolution, high signal-to-noise Magellan/MIKE spectrum. J1521-3538 shows the largest r-