IThis will happen billions of years in the future, but at some point our warm, friendly Sun will run out of all its fuel and end up becoming a white dwarf. This is a common fate for stars that are not massive enough to become black holes or neutron stars. Using an X-ray telescope orbiting Earth, researchers were able to peer into the heart of a unique “vampire” white dwarf system (EX Hydrae) for the first time, publishing their results. conclusions recently in Astrophysical Journal.
White dwarfs are incredibly dense—their mass of the Sun has been compressed into a space the size of Earth, and their gravitational pull is monstrous. When a white dwarf orbiting another star siphons material from the “donor star,” the binary star system is called a “cataclysmic variable.”
In addition to the strong gravitational tide, some white dwarfs also have a magnetic pull. In a catastrophic variable whose white dwarf has a sufficiently strong magnetic field, it can become a so-called “intermediate polar.” In this situation, in addition to attracting matter around the white dwarf, it will also attract matter towards its magnetic poles, which are perpendicular to the accretion disk. This is exactly the case in the vampire binary star system EX Hydrae.
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“If you could stand a little close to the white dwarf's pole, you would see a column of gas extending 2,000 miles into the sky and then fanning outward,” study co-author and MIT postdoc Sean Gunderson said in the report. statement. This 2,000-mile-high fountain of white-hot stellar material was larger than researchers previously thought—about half the radius of the white dwarf itself. Because the ejected material is so hot (temperatures reaching millions of degrees Fahrenheit), the curtain of scorching stellar matter emits X-rays. By measuring these X-rays, researchers were able to gain a better understanding of how star systems like EX Hydrae work.
The team plans to study other vampire white dwarfs in the future, and their studies could help us measure the size of the Universe. “There comes a point when so much material from a companion star falls onto the white dwarf that the white dwarf can no longer contain it, and it all collapses and produces a type of supernova that can be observed throughout the universe and can be used to determine the size of the universe,” astrophysicist and MIT co-author Herman Marshall. said.
This glimpse into the bizarre heart of a dying star may shed light on the nature and scale of it all.
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Main image: NASA/CXC/M.Weiss.
