The rushing dance to the death of the mysterious nebula

Two white dwarfs rotate very quickly around each other in a mysterious nebula. The distance between them is so small that they will surely become a star and explode.

Dr. Henri Boffin, an astronomer working for the Southern European Observatory, and some colleagues used the huge telescope on Chile's Atacama desert to follow Henize 2-428, a giant cloud of gas 4,000 light-years from Earth. It was born after a red giant star died, blowing material into the surrounding space to turn into a white dwarf. Their original goal was to find out what caused the nebula to look bizarre.

About 4,000 light-years from Earth, Henize 4-284 is a strange shaped nebula.(Photo: SPL)

When looking at the central area of ​​the nebula, they found the two celestial bodies orbiting each other at extremely short distances, Nature reported.

The two bodies in the middle of the nebula are white dwarfs. In fact, they are the heaviest white dwarfs that humans have ever discovered.

To explode into a supernova, a white dwarf must increase its mass by accumulating more matter. They can accumulate matter by sucking matter from another star or merging with that star.

When analyzing parameters from image data, the team realized that they were observing a pair of extremely special objects. Each white dwarf has a mass equivalent to the sun and they revolve around each other for only 4.2 hours. According to Einstein's theory of relativity, the distance between them will decrease over time. In the process of getting closer, they will lose energy. Finally they bump into each other and become the only star, with a mass equivalent to about 1.8 times the sun.

All white dwarfs with 1.4 times more mass than the sun will not cool down, because the carbon in their cores will be so compressed that the fusion reaction will recur. Due to the existence of a fusion reaction, one day a white dwarf will explode to turn into a supernova. The explosion can occur after about 700 million years and the team considers it to be in group Ia, meaning enough power to destroy the star to ashes.

The two white dwarfs in the middle of the Henize 2-428 nebula are so close that they only need 4.2 hours to rotate around each other.(Photo: ESO)

"The formation of supernovae after the merging of two white dwarfs is only a theoretical phenomenon. The pair of white dwarfs in the Henize 2-428 nebula is empirical evidence of the phenomenon. " Dr. David Jones, a researcher from the Southern European Observatory, explained.

Although the explosion will occur 4,000 light-years from Earth, its brightness is still large enough for people on Earth to observe.

But Philipp Podsiadlowski, an Oxford astrophysicist in England, does not rule out another possibility: After merging, two white dwarfs will turn into supernova collapsing inside.

"If the supernova collapsed inside, after a short explosion, a very dense neutron star will come out , " he explained.