We have already met the largest stellar representative (“The biggest star in the Universe is expected to die quickly”). Now let's see what the smallest star in the universe looks like.
Comparative OGLE-TR-122 Sizes
Tiny stars are usually born in places with a small amount of hydrogen. The celestial body is considered to be a stellar body, within which the process of nuclear fusion is carried out. To do this, the object must contain at least 7.5% of the solar massiveness (theoretically).
Previously, OGLE-TR-122 was called the smallest star in the universe. It is located on the territory of the constellation Kiel. This is a double star, one of which refers to the type of main sequence. For the first time a couple noticed in 2005. The rotational speed around the center of mass covers 7.3 days.
Physically, one of the stars resembles the star of our system. But the second (OGLE-TR-122 B) refers to red dwarfs. The radius reaches 0.12 from the sun. When compared with Jupiter, the star is only 16% larger than the gas giant. In fact, it is approaching the lower mass limit.
Comparative Sizes 2MASS J0523-1403
Another tiny red dwarf 2MASS J0523-1403 was considered the second most recent candidate. The object lives on the territory of the constellation Hare with a distance of 40 light years from us. Its effective temperature is 2074 K. The radius is 0.086 solar, and the mass is less than 0.08 solar. Her physical indicators also balance on the verge of stellar parameters. It is believed that with massiveness of 0.012-0.07 solar there is a risk of transition to the stage of brown dwarfs (thermonuclear reactions stop and the stars cool down).
The smallest star
A focused image of the EBLM J0555-57 dual system, made by the Swiss 1, 2 meter Leonard Euler telescope at the ESO La Silla observatory
Since 2017, the title of the smallest star in the Universe belongs to EBLM J0555-57. This is a triple star system, located in the constellation Painter. Removed 600 light years from the solar system. One of the stars is approaching the theoretical stellar limit.
Stars A and B are considered an eclipsing binary system, but the third component C is the smallest star. By mass, it reaches 0.081 solar (85 times more massive than Jupiter). So you understand, it is equal to Saturn in radius. The researchers believe that if its massiveness reached 7% of the Sun, then the thermonuclear reaction would end, and a brown dwarf would appear before us.
So, EBLM J0555-57C - the smallest star to date. However, researchers continue to search and study the theoretical limit, when the star still supports nuclear fusion. May soon find a new candidate.