In the process of fusion, the impression of two white dwarfs of an artist; Depending on the combined mass, the system can explode in a thermonuclear supernova or accumulate in a heavy white dwarf with WD J0551 + 4135.
In the process of fusion, the impression of two white dwarfs of an artist; Depending on the joint mass, the system may explode in a thermonuclear supernova.
Or WD J0551 + 4135 is chained in a heavy white dwarf. “You can expect to see an outer layer of hydrogen, sometimes helium, or just a mixture of helium and carbon.”
“You don’t expect to see this combination of hydrogen and carbon, because there should be a thick layer of helium in the middle of the restriction. When we saw it, it made no sense.”
WD J0551 + 4135 was first identified in the ESA data study for the Gaia star mapping spacecraft. Dr. Holland and his colleagues followed the spectroscopy with the William Herschel telescope.
By breaking the light emitted by the star, astronomers were able to identify the chemical composition of their atmosphere and discovered that it contained unusually high levels of carbon.
Most are relatively light, about 0.6 times the mass of our Sun, but it is in a solar mass of 1.14, about twice the average mass. Despite being heavier than our Sun, it is compressed two thirds of the Earth’s diameter.
The age of the white dwarf is also a clue. Older stars orbit faster than younger stars than the Milky Way, and the object moves more than 99% of other nearby white dwarfs with the same cooling age, suggesting that this star is older than it seems.
“We have a composition that we can explain through normal stellar evolution, twice the average mass of a white dwarf and a kinematic age greater than the cold age.”
“We are very sure how a star becomes a white dwarf and shouldn’t do it. The only way to explain it is if it was created by merging two white dwarfs.”
The theory is that when a star in a binary system expands at the end of its life, it will wrap its mate, bringing its orbit closer to its orbit, reducing the first star. The same will happen when the second star extends.
In billions of years, the emission of gravitational waves will reduce the orbit forward to the point where the stars merge. While it is predicted that the white dwarf will merge, this would be particularly unusual.
There is also a limit to how large the resulting white dwarf can be: more than 1.4 solar masses are believed to explode in a supernova, although it is possible that these explosions may occur at a slightly lower mass.
The white dwarf probably disappeared about 1.3 billion years ago, but the two original white dwarfs may have existed billions of years ago. It is one of the few white dwarfs ever identified, and the only one through its creation.
Dr. “It’s not that there are many white dwarfs, but more than that you would expect to see if some of them are formed by fusion,” said Hollands.
“Perhaps the most exciting aspect of this star is that it must have still failed to explode as a supernova: these giant explosions are really important in mapping the structure of the universe, because they were detected at great distances.”