Speaker
Description
O-C shell mergers in massive stars are astrophysical sites for the production of many radioactive isotopes such as $^{40}\mathrm{K}$, which heats rocky exoplanets, and $^{44}\mathrm{Ti}$ and $^{60}\mathrm{Fe}$, which are observed in supernova remnants. Mixing prescriptions used in 1D stellar evolution models of stars with O-C shell mergers do not capture features seen in 3D hydrodynamic simulations, such as more efficient mixing that decreases near the boundaries.
In this talk I will present the results of modifying the mixing profile of an O shell during a merger of a $15~\mathrm{M_\odot}$ $Z=0.02$ star informed by 3D macrophysics. Across different mixing scenarios, the predicted pre-explosive yields of radioactive isotopes can vary by multiple orders of magnitude, and yields of $^{40}\mathrm{K}$, $^{44}\mathrm{Ti}$, and $^{60}\mathrm{Fe}$ in particular by factors of $788$, $60847$, and $46$ respectively. Further, depending on the mixing, the pre-explosive yields of $^{40}\mathrm{K}$ and $^{44}\mathrm{Ti}$ can be larger than the explosive contributions. I will discuss the implications of this work for understanding rocky planet heating and interpreting the signals from supernova remnants like Cassiopeia A.
| Career stage | Graduate student |
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