James Webb Telescope Finds Brown Dwarfs as Small as Twice Jupiter’s Mass
NASA’s James Webb Space Telescope (JWST) has made an unusual discovery in the nearby star-forming region IC 348, detecting brown dwarfs with masses as low as roughly twice that of Jupiter.
Located about 1,000 light-years from Earth in the constellation Perseus, IC 348 is an active region where clouds of gas and dust are producing new stars and other celestial objects. Webb’s infrared observations allowed astronomers to investigate objects that are extremely faint and difficult to detect.
Brown dwarfs occupy an unusual category between planets and stars. They form through the collapse of molecular clouds like stars, but they do not become massive enough to sustain ordinary hydrogen fusion in their cores. The newly identified objects are therefore providing researchers with an opportunity to study how small an object produced through star-formation processes can become.
The researchers used Webb’s NIRCam to identify potential brown dwarfs and subsequently used its NIRSpec instrument to study their spectra. The observations revealed objects with masses around twice Jupiter’s mass—only about 0.19% of the Sun’s mass. NASA says these are the least massive brown dwarfs known and that their existence challenges current models of star formation.
One particularly intriguing object appears to have a disk of material around it. Such disks can contain the raw ingredients from which planets form. Scientists therefore say it is possible that small planets could eventually form around an object that itself has only about twice Jupiter’s mass, although Webb has not detected planets there.
The observations also revealed powerful jets from young protostars in the region. These jets collide with surrounding gas and dust, creating glowing structures known as Herbig-Haro objects.
The discovery gives astronomers a new opportunity to investigate the boundary between planetary-mass objects and objects formed through stellar processes. It could ultimately lead to revisions in scientists’ understanding of how stars and brown dwarfs are born.
