Astronomers discover record star as small as the moon but with more mass than the sun – .

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Astronomers discover record star as small as the moon but with more mass than the sun – .


Astronomers have discovered the smallest but the most massive white dwarf star never seen.
According to a new study published Thursday in the journal Nature, the “very special” star has a mass greater than that of our sun, all wrapped up in a relatively small body, similar in size to our moon. It formed when two less massive white dwarf stars, which spent their lives as a pair orbiting each other, collided and merged.

At the end of their life, the vast majority of stars become white dwarfs, which are essentially smoldering corpses, in addition to being one of the densest objects in the universe alongside black holes and neutron stars. In about 5 billion years, our sun will become a red giant before finally suffering the same fate.

“It may sound counterintuitive, but the smaller white dwarfs are more massive,” lead author Ilaria Caiazzo said in a statement. “This is because white dwarfs do not have the nuclear combustion that holds normal stars against their own gravity, and their size is instead regulated by quantum mechanics. “

The highly magnetized dead star, named ZTF J1901 + 1458, is located relatively close to Earth, just 130 million light years away. It was discovered by the Zwicky Transient Facility (ZTF) at Caltech’s Palomar Observatory.

When the two white dwarfs merged, they combined to form a new star, about 1.35 times the mass of our sun, the most massive of its kind ever found. If either star had just a little more mass, the fusion would have resulted in an intense explosion called supernova.

The white dwarf ZTF J1901 + 1458 is approximately 2,670 miles in diameter, while the moon is 2,174 miles in diameter. The white dwarf is depicted above the Moon in this artistic representation; in fact, the white dwarf is located 130 light years away in the constellation Aquila.
Giuseppe Parisi

ZTF J1901 + 1458 also has an “extreme” magnetic field nearly a billion times stronger than the sun, spinning rapidly to complete a full revolution in just seven minutes. It takes about 27 days in the sun to rotate.

With a diameter of 2,670 miles, it is the smallest known white dwarf in the universe over 400 miles. By comparison, the moon is 2,174 miles in diameter.

“We grabbed this very interesting object which was not massive enough to explode,” explains Caiazzo. “We’re really looking at how massive a white dwarf can be. “

So what’s next for the rare star?

Researchers believe the star has a mass large enough to eventually evolve into a neutron star, which is usually formed when a star with a mass much greater than the sun explodes in a supernova. If their hypothesis is correct, it means that many neutron stars in the universe may have formed in this previously unknown manner.

“It’s so massive and dense that in its nucleus, electrons are captured by protons in the nuclei to form neutrons,” Caiazzo said. “Because the pressure of the electrons opposes the force of gravity, keeping the star intact, the nucleus collapses when enough electrons are removed. “

The star’s proximity to Earth and its young age – only around 100 million years or less – means that similar stellar phenomena can occur more frequently in our own galaxy.

“No one has consistently been able to explore short-term astronomical phenomena on this type of scale until now. The results of these efforts are amazing, ”said Kevin Burdge, who first spotted the star in sky footage.

But researchers say they’re just getting started.

“There are so many questions to be answered, such as what is the rate of white dwarf fusion in the galaxy, and is that enough to explain the number of Type Ia supernovae?” Said Caiazzo. “How is a magnetic field generated during these powerful events, and why is there such diversity in magnetic field strengths among white dwarfs?” Finding a large population of fusion-born white dwarfs will help us answer all of these questions and more. ”

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