| News / Space News |
New type of star gives clues to mysterious origin of magnetars
Magnetars are the strongest magnets in the Universe. These super-dense dead stars with ultra-strong magnetic fields can be found all over our galaxy but astronomers don’t know exactly how they form. Now, using multiple telescopes around the world, including European Southern Observatory (ESO) facilities, researchers have uncovered a living star that is likely to become a magnetar. This finding marks the discovery of a new type of astronomical object — massive magnetic helium stars — and sheds light on the origin of magnetars.
Artist’s impression of HD 45166, the star that might become a magnetar. Photo: ESO
Despite having been observed for over 100 years, the enigmatic nature of the star HD 45166 could not be easily explained by conventional models, and little was known about it beyond the fact that it is one of a pair of stars, is rich in helium and is a few times more massive than our Sun.
“This star became a bit of an obsession of mine,” says Tomer Shenar, the lead author of a study on this object and an astronomer at the University of Amsterdam, the Netherlands.
“Tomer and I refer to HD 45166 as the ‘zombie star’,” says co-author and ESO astronomer Julia Bodensteiner, based in Germany.
“This is not only because this star is so unique, but also because I jokingly said that it turns Tomer into a zombie."
Having studied similar helium-rich stars before, Shenar thought magnetic fields could crack the case.
Indeed, magnetic fields are known to influence the behaviour of stars and could explain why traditional models failed to describe HD 45166, which is located about 3000 light-years away in the constellation Monoceros.
Shenar's team had found that the star has an incredibly strong magnetic field, of 43 000 gauss, making HD 45166 the most magnetic massive star found to date.
“The entire surface of the helium star has a magnetic field almost 100,000 times stronger than Earth's,” explains co-author Pablo Marchant, an astronomer at KU Leuven’s Institute of Astronomy in Belgium.
This observation marks the discovery of the very first massive magnetic helium star.
Moreover, it provides clues to the origin of magnetars, compact dead stars laced with magnetic fields at least a billion times stronger than the one in HD 45166.
The team’s calculations suggest 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 around 100 trillion gauss — the most powerful type of magnet in the Universe.
Shenar and his team also found that HD 45166 has a mass smaller than previously reported, around twice the mass of the Sun, and that its stellar pair orbits at a far larger distance than believed before.
Furthermore, their research indicates that HD 45166 formed through the merger of two smaller helium-rich stars. (ESO)
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