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arXiv · 2202.04767

Ellipsars: Ring-like explosions from flattened stars

Marcus DuPont·Andrew MacFadyen·Jonathan Zrake
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Abstract

The stellar cataclysms producing astronomical transients have long been modeled as either a point-like explosion or jet-like engine ignited at the center of a spherically symmetric star. However, many stars are observed, or are expected on theoretical grounds, not to be precisely spherically symmetric, but rather to have a slightly flattened geometry similar to that of an oblate spheroid. Here we present axisymmetric two-dimensional hydrodynamical simulations of the dynamics of point-like explosions initiated at the center of an aspherical massive star with a range of oblateness. We refer to these exploding aspherical stars as "ellipsars" in reference to the elliptical shape of the iso-density contours of their progenitors in the two-dimensional axisymmetric case. We find that ellipsars are capable of accelerating expanding rings of relativistic ejecta which may lead to the production of astronomical transients including low-luminosity GRBs, relativistic supernovae, and Fast Blue Optical Transients (FBOTs.)

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Marcus DuPont, Andrew MacFadyen, Jonathan Zrake. 2022-02-09. Ellipsars: Ring-like explosions from flattened stars. https://doi.org/10.3847/2041-8213%2Fac6ded

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