Magnetars are the strongest magnets in the universe. These super-dense dead stars with super-strong magnetic fields can be found in our galaxy, but astronomers don’t know exactly how they formed. Using multiple telescopes around the world, including those at the European Southern Observatory (ESO), researchers have now discovered a living star that could most likely transform into a magnetar. This discovery marks the discovery of a new type of astronomical object—massive magnetic helium stars—and sheds light on the origin of magnetars.

Despite being observed for over 100 years, HD 45166’s mysterious nature was not easily explained by conventional models, and little was known about it except for the fact that it was one of a helium-rich double star and had a mass several times greater than itself. our sun.

“This star has become my obsession,” says Tomer Shenar, lead author of a study published on the object. Science and an astronomer from the University of Amsterdam, Netherlands. “Thomer and I call HD 45166 a ‘zombie star’,” says Julia Bodensteiner, co-author and ESO astronomer from Germany. “Not only because this star is so unique, but also because I jokingly said it turned Tomer into a zombie.”

Chenard, who had previously studied similar helium-rich stars, believed that magnetic fields could solve this problem. Indeed, magnetic fields are known to affect the behavior of stars, and this may explain why conventional models fail to identify HD 45166, located about 3,000 light-years away in the constellation of the Unicorn. “‘What if the star is magnetic?’ “I remember reading the literature,” he says.

Using several facilities around the world, Chenard and his team set out to study the star. Key observations were made in February 2022 on the Canada-France-Hawaii Telescope, an instrument that can detect and measure magnetic fields. The team also relied on key archival data obtained by the Optically Enhanced Extended Range Optical Spectrograph (FEROS) at ESO’s La Silla Observatory in Chile.

After the observations were complete, Chenard asked co-author Gregg Wade, an expert on magnetic fields in stars at the Royal War College of Canada, to examine the data. Wade’s response confirmed Shenard’s guess, “Dude, whatever it is, it’s definitely magnetic.”

Chenard’s team found that this star has an incredibly strong magnetic field of 43,000 Gauss, making HD 45166 the most magnetic star ever found. “The entire surface of a helium star is as magnetic as the strongest man-made magnets,” explains co-author Pablo Marchant, an astronomer at the KU Leuven Institute for Astronomy in Belgium. This observation marks the discovery of the first massive magnetic helium star. “This is an exciting discovery of a new kind of astronomical object,” says Chenard, “especially if it was hidden from view all along.”

It also provides clues about the origins of magnetars, compact dead stars filled with magnetic fields at least a billion times stronger than HD 45166. The team’s calculations show that this star will end its life as a magnetar. As it collapses under its own gravity, its magnetic field will strengthen and the star will eventually become a very compact core with a magnetic field of about 100 trillion gauss, the strongest type of magnet in the universe.

Chenard and his team also found that HD 45166 has a lower mass than previously reported, is about twice the mass of the Sun, and orbits the stellar pair at a much greater distance than previously thought. In addition, their research shows that HD 45166 is formed by the merger of two small helium-rich stars. “Our findings completely change our understanding of HD 45166,” concludes Bodensteiner. Source