It is the first heavy helium magnetar ever discovered.
A hundred years ago, astronomers saw the star HD 45166 twinkle in the night sky. But all that time they didn’t really know what they were seeing. All that was known about the mysterious star was that it is part of a binary star, contains a lot of helium and is many times more massive than our Sun. in New study Researchers revealed its mysterious nature. It turned out to be an unknown type of star, which is likely to become a magnetar.
HD 45166 is located about 3,000 light-years away in the constellation of the Unicorn. For some time, researchers have been trying to figure out the mysterious nature of the strange star. But this is not easy to explain with traditional models. “This star has become a bit of an obsession for me,” says Tomer Şennar, an astronomer at the University of Amsterdam and lead author of the new paper. “Tomer and I call HD 45166 a ‘zombie star,’” adds co-author and ESO astronomer Julia Bodensteiner. “It’s not only because this star is unique, but also because I jokingly commented that it turns Shinar into a zombie himself.”
Shinar, who has previously studied similar helium-rich stars, suggested that HD 45166 may have a strong magnetic field. It is known that magnetic fields influence the behavior of stars. This may explain why current models fail to characterize the star. “I remember a flashlight came to my mind when I was browsing through the existing literature,” Schnarr says. “What if a star is magnetic?”
The researchers turned to several facilities around the world, incl Canada-France-Hawaii Telescope, which is equipped with an instrument that can detect and measure magnetic fields. In addition, the team made use of significant archival data collected with Fiber-fed extended-band optical spectrometer (FEROS) from ESO’s La Silla Observatory in Chile. After analyzing the notes, it was clear. “Whatever that thing is, it’s definitely magnetic,” said study co-author Greg Wade, an expert on magnetic fields in stars.
Most massive magnetar ever
HD 45166 appears to have an incredibly strong magnetic field, up to 43,000 gauss. This means that the star is the most massive magnetar ever seen. “The entire surface of a helium star is magnetic, as is the strongest man-made magnet,” said co-author Pablo Marchant.
This animation shows HD 45166, a massive star recently discovered to have a magnetic field of 43,000 gauss – the strongest magnetic field ever found in a massive star. Strong winds of particles blowing away from the star are captured by this magnetic field, and the star is enveloped in a gaseous envelope, as shown here. Video: ESO/L. Calcada
A new kind of star
This means that researchers have found a new type of star. Because HD 45166 is the first heavy helium magnetar ever discovered. “It’s great that a new type of astronomical object has been discovered,” Schnarr says. “Especially if she’s in front of us the whole time.”
But that’s not the only thing special about HD 45166. The star also provides clues about the mysterious origin of magnetic trains. These highly compressed, extinct stars have super strong magnetic fields – in fact, they are the strongest magnets in the universe. Although they can be found throughout our Milky Way galaxy, astronomers still don’t know exactly how they form. But HD 45166 is now lifting a corner of the veil.
More about magnetism
A magnetar is a rare type of star with an extremely strong magnetic field. These extinct coherent stars are surrounded by magnetic fields at least a billion times stronger than those in HD 45166. In addition, they can produce powerful bursts of energy. Magnetars are actually very rare neutron stars: the highly compact remnants of exploding massive stars. The neutron star rotates rapidly, has a strong magnetic field and has a diameter of about 20 kilometers, but its mass is greater than that of the Sun. Magnetars are young neutron stars, which have an exceptionally strong magnetic field. To date, only a few dozen have been discovered.
The team’s calculations indicate that the star will end up as a magnetar. As it collapses under its own gravity, its magnetic field will grow stronger and stronger. HD 45166 is expected to eventually turn into a very compact core with a magnetic field of about 100 trillion gauss – the strongest type of magnet in the universe. So the heavy magnetar helium sheds light on how magnetars form.
In addition, the researchers are tuning the properties of HD 45166. For example, they have found that HD 45166 has a smaller mass than previously thought — about twice the mass of the Sun. It also appears that the pair of stars orbit each other at a much greater distance than previously assumed. Finally, the study indicates that HD 45166 formed from the merger of two smaller, helium-rich stars. “Our findings provide a completely new picture of HD 45166,” concludes Bodensteiner.
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