Sensitivity of He Flames in X-ray Bursts to Nuclear Physics

Through the use of axisymmetric 2D hydrodynamic simulations, we further investigate laterally propagating flames in X-ray bursts (XRBs). Our aim is to understand the sensitivity of a propagating helium flame to different nuclear physics. Using the Castro simulation code, we confirm the phenomenon of enhanced energy generation shortly after a flame is established after by adding ${}^{12}$C(p, ${\gamma}$)${}^{13}$N(${\alpha}$, p)${}^{16}$O to the network, in agreement with the past literature. This sudden outburst of energy leads to a short accelerating phase, causing a drastic alteration in the overall dynamics of the flame in XRBs. Furthermore, we investigate the influence of different plasma screening routines on the propagation of the XRB flame. We finally examine the performance of simplified-SDC, a novel approach to hydrodynamics and reaction coupling incorporated in Castro, as an alternative to operator-splitting.Comment: 18 pages, 17 figure

Dynamics of Laterally Propagating Flames in X-ray Bursts. I. Burning Front Structure

We investigate the structure of laterally-propagating flames through the highly-stratified burning layer in an X-ray burst. Two-dimensional hydrodynamics simulations of flame propagation are performed through a rotating plane-parallel atmosphere, exploring the structure of the flame. We discuss the approximations needed to capture the length and time scales at play in an X-ray burst and describe the flame acceleration observed. Our studies complement other multidimensional studies of burning in X-ray bursts.Comment: Submitted to Ap

Comparing Early Evolution of Flames in X-Ray Bursts in Two and Three Dimensions

We explore the early evolution of flame ignition and spreading on the surface of a neutron star in three dimensions, in the context of X-ray bursts. We look at the nucleosynthesis and morphology of the burning front and compare to two-dimensional axisymmetric simulations to gauge how important a full three-dimensional treatment of the flame is for the early dynamics. Finally, we discuss the progress toward full-star resolved flame simulations

pynucastro/pynucastro: pynucastro 2.1.0

add eval_zbar() to Composition (#632) fix get_rate_by_name to work with "pp" reactions (#632) created a method to reduce a Composition from one set of nuclei to another based on the nuclei masses and charge number (#625) switch AmrexAstroCxxNetwork to do bilinear interpolation in terms of log(T) and log(rhoY) (#592, #611) tabular rates in python now do linear interpolation (#602) added an example of creating a custom rate (#615) Rate now calls _set_q() to set the Q value if it is not passed in (#617) added a TableInterpolator that works both for interactive python and PythonNetwork (#612, 610, 609) added a RateCollection method to find duplicate links (#601) python networks with tabular rates now copy the table files (#605) added a get_nuclei_in_range method to return a range of nuclei (#593) we now do a binary search in the C++ partition function interpolation (#581) added a simple C++ network (SimpleCxxNetwork) (#591, #585) added the weak rates from Langanke 2001 (#536) cleaned up partition functions in C++ (#578, 573, 569, 565) converted the Suzuki tabular rates to be in terms of log (#550) fixed a bounds issue in C++ table interpolation (#566) eliminated a variable length array in the C++ table interpolation (#567) added rate indices to the C++ networks (#563) added a network reduction algorithm (#529, #528, #527, #526, #525, #523) added a molar fraction method to Composition (#546) added examples of interfacing with Julia (#539) added a code of conduct (#504) added gamma heating to tabular weak rates (#502