Most massive white dwarf found

(ORDO NEWS) — At the end of their life cycle, the depleted reserves of hydrogen fuel, sun-like stars begin to expand, turning into red giants. At some point, all thermonuclear reactions stop at the core of a dying star. As a result, the star sheds the outer layers of its atmosphere, and its core shrinks, turning into a white dwarf.

According to modern theoretical models, the mass of white dwarfs should be in the range from 0.6 to 1.44 solar. If such an object crosses the upper limit, called the Chandrasekhar limit, this leads to a type Ia supernova explosion. The white dwarf collapses into a neutron star, which is accompanied by the release of a huge amount of energy.

Recently, a group of Russian astronomers announced the discovery of a white dwarf with the largest known mass. The object, designated WD 1832 + 089, is located 243 light-years from the Sun. Its radius is 2500 km, which is comparable to the radius of Mercury. The mass of WD 1832 + 089 is 1.33 times that of the sun, which is a record for objects of this class. It makes one revolution around its axis in just 353 seconds.

According to the researchers, WD 1832 + 089 is hardly a product of the evolution of a single massive star. For this, its rotation speed is too high. It is much more likely that it was formed as a result of the merger of two white dwarfs, whose total mass was less than the Chandrasekhar limit. Therefore, the event did not lead to a supernova explosion. According to astronomers’ calculations, the merger should have happened about 330 million years ago.


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