Thursday, May 16, 2019

The Production of Heavy Elements via Collapsars

The gold in your jewelry and the uranium powering nuclear reactors might seem entirely unrelated. However, in a paper published in Nature, two astrophysicists suggest that many of the heavy elements found throughout the universe are created as a result of a collapsar, a rare kind of supernova.

Collapsars occur when a rapidly-rotating, high-mass star collapses into a black hole, causing the outer layers to explode in a supernova. As the star dies, its core undergoes a catastrophic gravitational collapse resulting in the formation of a black hole, leading to the supernova explosion of the outer shell. Then, the remnants of the star fall into orbit around the black hole, creating a vortex of high-energy lighter elements. In this extreme scenario, the conditions are right enough to allow a nuclear process known as the r-process take place, causing many of the heavy elements of the universe to form.

It was previously thought that the majority of elements formed via the r-process were a result of neutron star mergers. Nonetheless, a recent analysis of the galactic abundance of one of these r-process elements, europium, seems to indicate that a different mechanism was supplying the universe with the multitude of heavy elements we see today.

The authors of this study identify collapsars as a likely source. In fact, over 80% of r-process elements could be formed via collapsar-catalyzed nuclear reactions. Although collapsars are much rarer than neutron star mergers, they produce a much greater quantity of these r-process elements, explaining  why they create the majority of heavy elements in the universe.

Read the official research paper here:

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