The magnetism of HD 45166 is 100,000 times stronger than that of the Earth and after its explosion it would be much greater.

A mysterious star has puzzled astronomers for a century, and finally they discovered features that reveal its nature. HD 45166, described in a Science magazine publication, is the most magnetic Wolf-Rayet star known and is destined to become one of the most magnetic objects in the universe, whose origin was unknown until now: magnetars.

Magnetars are neutron stars (stellar remnants) with extremely strong magnetic fields, which is why they are considered the strongest magnets in existence. According to the study, its origin is possibly due to the amplification of a magnetic field in the core of a parent star after a supernova explosion (the stellar terminal phase).

Thus, the Wolf-Rayet presents the conditions to become a magnetar. “Stellar evolution calculations indicate that this component will explode as a supernova and that its magnetic field is strong enough to leave behind a magnetar remnant,” the document states. Multiple observatories in different parts of the world were used for the research.

How is HD 45166?
The star HD 45166 is rich in helium and is slightly more massive than the Sun, indicates a scientific statement from the European Southern Observatory (ESO). It is located about 3,000 light-years away, in the constellation Monoceros.

Its magnetic field is 43,000 gauss, making it the most magnetic massive star. “The entire surface of this helium star has a magnetic field about 100,000 times stronger than Earth’s,” said Pablo Marchant, co-author astronomer of the study.

HD 45166 is expected to go supernova in a few million years. Its collapsed core will contract and concentrate a magnetic field that will become a magnetar with a magnetism of 100 trillion gauss intensity, according to estimates.

“It is exciting to discover a new type of astronomical object, especially when it has been hiding in plain sight all along,” Tomer Shenar, an astronomer at the University of Amsterdam who led the research, said in the ESO statement.

source: N. Langer, Presupernova Evolution of Massive Single and Binary Stars. Annu. Rev. Astron. Astrophys.50, 107–164 (2012).

4S. E. Woosley, The Evolution of Massive Helium Stars, Including Mass Loss. Astrophys. J.878, 49 (2019).