2023-08-17 18:00:08
Artist’s impression of a massive, magnetic star in the binary system HD 45166, which may be the origin of magnetars. FABIAN BODENSTEINER
The Milky Way always conceals unexpected treasures, strange celestial objects, with properties never seen before. And which can shed new light on certain gray areas.
This is what happens thanks to a pair of stars, yet observed for just over a century, located in the constellation of the Unicorn, more than 3,000 light years from Earth. The pair, called “HD 45166”, is made up of two fairly massive stars, respectively 3.4 and 2 times the mass of the Sun, which revolve around each other in one hundred and twenty-eight days. The lightest member of the duo could explain one of the mysteries of the cosmos: the formation of objects as compact as a black hole and emitting a gigantic magnetic field, the magnetars. By “gigantic” we are talking about more than 10 billion teslas, or about 1,000 billion times more than the average magnetic field of the Sun, or 200,000 billion times more than the Earth’s magnetic field.
These magnetars, of which more than twenty have been observed in our galaxy, belong to the large family of neutron stars, very dense stars with a radius of ten kilometers, but weighing as much as one and a half times the Sun. This is often how giant stars end their lives, having burnt up their hydrogen and collapsing in on themselves. Pulsars are special neutron stars, which emit regular radio waves towards the Earth. And magnetars are another category, provided with very intense magnetic fields, but of unknown origin.
“Obsessed with HD 45166”
This is where HD 45166 and an international collaboration of fifteen researchers who publish their observations in ScienceAugust 17. “I had been obsessed with HD 45166 for several years, because what we knew about this system did not fit. I read everything that happened about him., remembers Tomer Shenar, today at the Madrid Astrobiology Center. Officially, the least massive star in the HD 45166 system was classified as a Wolf-Rayet star, a star composed of helium, which has lost its hydrogen and which emits strong winds, ejecting the surrounding material several hundred kilometers away. hour. “But it was less luminous than the others in this category. Its winds were ten times less strong »notes Tomer Shenar who adds that his light signature, or spectrum, did not correspond to his family either: in addition to helium, a lot of carbon, oxygen and nitrogen… In addition, this spectrum is very variable over time, some elements literally disappearing.
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