Traces of a possible magnetorotational hypernova have been found

SMSS 2003-1142 at the center (Image courtesy Da Costa/SkyMapper)
SMSS 2003-1142 at the center (Image courtesy Da Costa/SkyMapper)

An article published in the journal “Nature” reports the identification of what is considered a magnetorotational hypernova, the explosion of a very massive star with a powerful magnetic field and in rapid rotation. A team of researchers led by David Yong, Gary Da Costa, and Chiaki Kobayashi collected evidence of this type of hypernova for the first time. That was achieved by examining the data collected not directly but by investigating a mysterious red giant star discovered in the Milky Way halo and cataloged as SMSS J200322.54-114203.3, or simply SMSS 2003-1142, in which there are anomalous quantities of some chemical elements explainable as the product of a magnetorotational hypernova.

About 7,500 light-years away from Earth, the red giant star SMSS 2003-1142 was discovered in 2018 and exhibited truly anomalous characteristics. It has an iron-hydrogen ratio about 3000 times lower than the Sun’s and that’s already a very rare fact. At the same time, it contains much greater than expected amounts of some heavy elements making it even rarer, to the point that David Yong called it a needle in a haystack.

Astronomers expect each generation of stars to contain a certain amount of elements heavier than hydrogen and helium produced by previous generations. Each supernova and hypernova scatters new heavy elements into interstellar space that will help form new stars and new planets. In the case of the star SMSS 2003-1142 the accounts don’t add up but this new research offers a solution.

An article published in the journal “Monthly Notices of the Royal Astronomical Society” in May 2005 reported a model describing the possibility of a magnetorotational supernova. In the case of the elements present in anomalous quantities in the star SMSS 2003-1142, the origin could be in an even more catastrophic event: a hypernova. That type of explosion can occur in very massive stars which, in the course of their agony, eject the outer layers which contain many heavier chemical elements, up to iron.

According to the researchers, about 13 billion years ago, the star SMSS 2003-1142 was formed from a soup of chemical elements that contained the remains of a magnetorotational hypernova. According to Nobel laureate in physics Brian Schmidt, who conducted various studies on supernovae and leads the SkyMapper project that discovered SMSS 2003-1142, the high zinc abundance is a clear indicator of a hypernova. The combination of elements found indicates that that hypernova occurred in a rapidly rotating, strongly magnetized star.

The traces of a possible magnetorotational hypernova are indirect since they were found in the star SMSS 2003-1142 and not in observations of the event or at least of its remains. This leaves open the possibility that the anomalous set of elements is the result of more than one event of a different type such as the merger of neutron stars. It’s normal for the various possibilities to be examined and checked by other scientists. The authors of this study hope to find other stars with a similar composition to find more traces of these very rare catastrophic explosions.

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