Magnetars and other oddities

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The spectral information that made us check the star's appearance also provided information about its magnetic field . Magnetic fields influence the polarization of light, and the researchers obtained this polarization using light emitted by a series of ions that were trapped within the Wolf-Rayet star's own magnetic field. This data was used to provide an estimate of the strength of said magnetic field, which turned out to be in the area of ​​40,000 Gauss. For comparison, the Earth's magnetic field is less than 1 Gauss.

While the star is relatively light at twice the mass of the Sun, it is still large eno Phone Number List ugh to end up in a supernova, which in turn leaves behind a neutron star. That neutron star should have a radius of the order of a dozen kilometers. If you keep the 40,000 Gauss magnetic field on the surface of the star, but compress it to the new 12 kilometer radius surface, then you end up with a magnetic field strength of about 1,014 Gauss, which means you have a magnetar. So, that Wolf-Rayet star is a magnetar precursor, the first one we've seen.

But it's also unlike any other Wolf-Rayet star we've seen, so the research team investigated its history through simulations. These suggest that the normal companion star is simply too far away to have a major influence on the evolution of the system. Instead, HD 45166 likely began as a three-star system , with the Wolf-Rayet star originally being two stars orbiting each other at a short distance. Their interactions led to a period in which their two helium-rich cores shared a single hydrogen-rich shell.

The two nuclei spiraled inward and fused, expelling hydrogen in the process. What was left was a small helium-rich star with an intense magnetic field . That magnetic field trapped some of the material that might otherwise be ejected, producing the spectral lines that helped researchers figure out what was happening.



That's quite a different set of circumstances, which might suggest that these precursors are rare. But it is estimated that up to 10% of neutron stars go through a magnetar phase, which should mean they are reasonably common. How do we explain this discrepancy?

The researchers suggest that we may have already observed some similar stars. The only reason we were able to figure out this system is the presence of a companion star, and that is not common for Wolf-Rayet stars. So it may be that we have already observed similar stars, but have not been able to recognize them.