Saturn-sized: The smallest star is found

An international team of astronomers has reported the discovery of one of the smallest stars, inside which thermonuclear reactions occur. It is comparable in size to Saturn.

Binary system consisting of white dwarf and ordinary star in the artist’s image. Source: Mark Garlick/Getty Images

The discovery was made during the study of the TMTS J0526 system, located at a distance of 2,760 light-years from Earth. Its main component is a white dwarf, which has a mass of 0.73 solar, and a diameter about 10 times smaller than the diameter of the Sun.

Its companion is a star in the depths of which thermonuclear reactions involving helium occur. Its mass is 0.33 solar, and its diameter is only 7 times the diameter of the Earth (about 90 thousand km). Thus, it is one of the smallest stars known to us. It is even smaller than Saturn, which has a diameter of 116 thousand km.

Both objects are separated by a short distance. They orbit around a common center of gravity with a period of only 20 minutes. The gravity of the white dwarf gradually deforms the star. In about 1.5 million years, it will overflow its Roche lobe. This will lead to the fact that the white dwarf will begin to absorb the matter of its companion, and the orbital period will decrease at first to 14, and then 9 minutes. Eventually, the star will turn into a white dwarf, after which it will begin to expand and move away from its companion again.

According to

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