Astronomers identify a new type of star explosion called a magneto-rotational hypernova

Shane McGlaun - Jul 8, 2021, 4:53am CDT
Astronomers identify a new type of star explosion called a magneto-rotational hypernova

An international team of astronomers has discovered the first evidence of the destruction of a collapsed and rapidly spinning star in a phenomenon they have called a magneto-rotational hypernova. This is a new type of explosion that was previously unknown and is said to have occurred only about a billion years after the Big Bang. Researchers believe the new type of explosion is the most likely explanation for the presence of unusually high amounts of some elements detected in another extremely ancient and primitive Milky Way star.

The star is known as SMSS J200322.54-114203.3, and it contains more elements such as zinc, uranium, europium, and potentially gold and other stars of the same age. Researchers say that neutron star mergers, which is the accepted source of the material needed to forge those types of metals, aren’t enough to explain the presence of those elements. Astronomers calculated that only the violent collapse of a very early star, amplified by rapid rotation and the presence of a strong magnetic field, could account for the additional neutrons required.

Researcher Dr. Simon Murphy says the chemical fingerprint of a star can tell scientists a lot about its age and the environment where it was born. He says the lack of heavy elements in the star’s atmosphere tells us the star is extremely old, but it is oddly abundant in heavy elements like zinc, uranium, and europium. Murphy says the fingerprint is a sign that the star was created from gas enriched by the explosion of a very massive, highly-magnetized, and fast rotating star.

Murphy believes the explosion was more powerful than a supernova, which the team has called a magneto-rotational hypernova. He notes that this is the first time astronomers have seen the chemical fingerprint of a hypernova explosion. He hopes the discovery will prompt new theoretical work to understand that type of powerful explosion.

The star in question has an iron-to-hydrogen ratio about 3000 times lower than the sun, which is very rare. Astronomers call that an extremely metal-poor star. While having less metal than expected, it contains a much larger than expected amount of heavier elements making it even rarer.

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