The "Clocked burster", GS 1826—238 is one of the best studied burst sources, due to it's (mostly) consistent and regular bursts. However there's long been some uncertainty about the fuel composition, with some studies suggesting metal-rich fuel, and others metal-poor. (Here by "metals" we mean an even more restrictive set than usually meant by astronomers, of the CNO nuclei that contribute to steady H-burning prior to ignition).

Now Monash PhD graduate Zac Johnston has resolved this uncertainty, with the most comprehensive observation-model comparison to date. He assembled a grid of almost 4000 KEPLER runs and performed a comparison to the observational data, via a novel interpolation scheme which speeds up the calculations by many orders of magnitude. His results confirm the "metal rich" scenario, and also provide constraints on the source distance and system inclination. His paper was just accepted by MNRAS. If you want to do your own burst comparisons, you can also check out the simulation grid data.

Read the paper (arXiv:1909.07977)

Labels: 2020, /postgrads