A white dwarf with a record density and a huge mass compared to its small size has been discovered in the Milky Way, about 130 light-years from Earth.
The researchers report that the highly magnetic, fast-spinning white dwarf is 35 percent larger than the sun, but 4,300 kilometers in diameter, slightly larger than the moon. This means that it has a greater mass than all white dwarfs known so far, but it is smaller, and its density is enormous.
While the period of rotation of the Sun on its axis is about 27 days, the period of rotation of the white dwarf is seven minutes. Its magnetic field is a billion times stronger than that of the Earth.
White dwarfs represent the final stage of star evolution, and are usually about the size of Earth and a hundred times smaller than the Sun. Its mass is approximately equal to the mass of the Sun, so its density is very high. White dwarfs have extremely high surface temperatures, and therefore emit bright white light.
Only two other types of celestial bodies, black holes and neutron stars, have a higher density than white dwarfs.
The birth of ZTF J1901+1458, a white dwarf, was also unusual, noted Kevin Bridge of Palomar Observatory at the University of California, California Institute of Technology near San Diego. It appears to be the product of a binary star system in which two stars orbit each other. At the end of their life cycle, these two stars separately turned into white dwarfs, then spiraled toward each other and melted into one unit.
With a slightly higher density, the result of the merger would be a massive starburst, or supernova, said Ilaria Caiso, an astrophysicist at Caltech and lead author of a study on the discovery in the scientific journal Nature. According to Caiazzo, this white dwarf has really extreme qualities.
We’ve found an object that’s about to find out how small and massive a white dwarf is.
Adding that the orb could explode at any time. The white dwarf gradually shrinks, making it more dense. If it does not explode, it can cause its core to collapse, making it a neutron star. This may be a previously unknown pathway for neutron star formation, MTI writes.