A white dwarf is not your type of star.
Although main-sequence stars, such as our Sun, fuse nuclear material into their nuclei to prevent it from collapsing under its own weight, white dwarfs use an effect known as quantum degeneration. The quantum nature of electrons means that no two electrons can have the same quantum state.
When you try to press the electrons in the same state, they exert a degenerative pressure that prevents the white dwarf from collapsing.
But there is a limit as to the mass a white dwarf can have.
Subrahmanyan Chandrasekhar made a detailed calculation of this limit in 1930 and found that if a white dwarf has more mass than about 1.4 suns, gravity will crush the star into a neutron star or black hole.
But Chandrasekhar’s limit is based on a fairly simple model. One where the star is in balance and does not rotate. Real white dwarfs are more complex, especially when they collide.
Binary white dwarfs are quite common in the universe. Many Sun-like stars and red dwarfs are part of a binary system.
(ESA / XMM-Newton, L. Oskinova / Univ. Potsdam, Germany)
When these stars reach the end of their main sequence life they become a binary system of white dwarfs.
Over time, their orbits can decay, eventually causing the two white dwarfs to collide. What happens next depends on the situation.
They can often explode as a new or supernova, creating a remnant neutron star, but can sometimes form something more unusual, such as a recent article published in Astronomy and astrophysics shows.
In 2019 an X-ray source was discovered that looked similar to a white dwarf, but was too bright to be caused by a white dwarf. It was suggested that the object could be an unstable fusion of two white dwarfs. In this new study, a team used the XMM-Newton X-ray telescope to capture an image of the object, seen above.
They confirmed that the object has a mass above the Chandrasekar limit. The super-Chandrasekar object is surrounded by a remnant nebula with high wind speeds.
The nebula is made up mostly of neon, seen as green in the image above. This is consistent with the object created by a fusion of white dwarfs. It probably has a high rotation, which prevents the object from collapsing into a neutron star.
Eventually, this object will collapse and become a neutron star in the next 10,000 years. It will probably create a supernova in the process. It seems that a white dwarf can break Chandrasekhar’s boundary, but only for a while.
This article was originally published by Universe Today. Read the original article.