Researchers from the National Astronomical Observatory of the Chinese Academy of Sciences based on
Astronomers say that the stars they have found are veryclose to us, 80% of them are within 326 light-years, and the farthest is at a distance of 1174 light-years. Their kinematic age is about 300 million years, and their kinematic characteristics and metallicity are similar to the stars of the Milky Way.
According to the authors of the work, all ultra-coldthe dwarfs in the sample are brown dwarf candidates. At the same time, 77 of them have lithium absorption lines in their spectra, which indicates a very high probability that they are brown dwarfs.
Ultracold dwarfs have a small mass,red color and low brightness. Due to their low brightness, they are very difficult to observe, and the requirements for observation devices are extremely high. Therefore, studies of such stars began only in recent decades.
Brown dwarfs are substellar objects withoutstable hydrogen fusion in the nucleus. Brown dwarfs can support thermonuclear reactions, but the power of such reactions is too weak. Such stars do not reach constant luminosity, but shrink and dim.
Researchers say the analysis of browndwarfs plays a significant role in studies of the history of the formation of the Milky Way, the initial mass function and hot planetary atmospheres. In addition, brown and ultracool dwarfs are ideal candidates for searching for rocky terrestrial planets: they are so dim that it is easier to detect planets with very low mass around them.
Cover image: NASA/JPL-Caltech
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