An international team of astronomers has discovered the smallest known brown dwarf star using the James Webb Space Telescope. The free-flying object has a mass just three to four times the mass of Jupiter, according to the study published in the Astronomical Journal, making it difficult to explain using modern concepts. Brown dwarfs are intermediate connections between gas giants and low-mass stars. They form like stars and collapse under the influence of their own gravity, but they never become dense enough to trigger thermonuclear reactions that burn hydrogen.
The NIRCam near-infrared camera and NIRSpec spectrometer were able to identify three targets with masses between three and eight Jupiters and surface temperatures between 830 and 1500 degrees Celsius. The smallest of the candidate objects has a mass three to four times that of Jupiter, and its formation is difficult to explain with current theoretical models. Two of the three brown dwarfs identified in this study exhibit spectral features caused by the presence of unknown hydrocarbons in their atmospheres. The same infrared signature was detected by NASA’s Cassini mission in the atmospheres of Saturn and its moon Titan, as well as in the interstellar medium. This is the first time this molecule has been detected in the atmosphere of an object outside our solar system.