Star-forming Region IC 348 in Perseus: Brown Dwarf Stars | Webb Telescope
Image Description: A star-forming region. It is blanketed in thick clouds of gas and dust, millions of kilometers across, that form swirling patterns. Bright stars are scattered throughout the clouds with the densest cluster situated in the center of the scene. Each is crowned with six long points created by the optics of the telescope’s mirrors. In the upper right, a couple of hidden stars blast out long, glowing jets of material.
IC 348 is a star-forming region in the constellation Perseus located about 1,000 light years from the Sun. This is one of the largest images from the NASA/European Space Agency/Canadian Space Agency James Webb Space Telescope released to the public so far. Using Webb, astronomers searched IC 348 for brown dwarfs that are less massive than the smallest stars. The researchers discovered brown dwarfs just twice the mass of Jupiter, bringing the study of these curious objects into a new mass range.
In regions like IC 348, cold clouds of molecular hydrogen gas collapse to form new stars, creating glowing, sculpted scenes like this one. The star-formation process can create impressively varied objects, from massive stars that expire after only a few million years in core-collapse supernova explosions to the smallest and most common stars that are long lived and produce powerful stellar storms.
The smallest stars weigh in at around 8% of the Sun’s mass. Below this mass lies a strange and intriguing class of objects called brown dwarfs. Brown dwarfs form in the same way that stars do, through the collapse of molecular clouds, but unlike stars, the cores of brown dwarfs never become hot enough to fuse hydrogen into helium (though many briefly fuse deuterium, or heavy hydrogen, early in their lives).
What is still not clear—and what researchers hoped to learn by using Webb’s sensitive instruments to probe IC 348—is how small are the smallest objects created by the star-formation progress.
In other words, how small is the smallest brown dwarf?
Researchers seeking to answer this question first used Webb to study IC 348 in 2022, when they discovered brown dwarfs with masses as low as three to four times the mass of Jupiter. Now, the same research team has used Webb to probe even deeper into this region in search of even smaller brown dwarfs.
The team used Webb’s Near-Infrared Camera (NIRCam) in 2024 to capture the warm glow of young brown dwarfs and newborn stars that we see in this new image of IC 348. After selecting candidate brown dwarfs based on their colors and brightness, they followed up with Webb’s Near-Infrared Spectrograph (NIRSpec) in 2025 to conduct spectroscopic observations to study the masses of the brown dwarfs.
These deep Webb observations revealed something remarkable—brown dwarfs with masses as low as just twice the mass of Jupiter—just 0.19% of the Sun’s mass. These are the least massive brown dwarfs known, and their existence poses a challenge to models of how stars form.
In addition to the discovery of these unexpectedly lightweight brown dwarfs, the Webb observations contained even more surprises. One of the lightest newfound brown dwarfs showed signs of a disc, suggesting that planets could be forming around it despite the brown dwarf being the mass of a planet itself.
While inspecting the spectra of IC 348’s brown dwarfs, the research team also found a feature that they attributed to hydrocarbons, molecules made only of hydrogen and carbon atoms. This feature has only been seen in the atmospheres of the lowest-mass brown dwarfs, suggesting that these extreme objects might exist in a spectral class of their own.
The stars and brown dwarfs of IC 348 are not the only attractions in this photo. A brilliantly detailed collection of protostars occupies the upper-right corner of the image. Several of these protostars are accompanied by Herbig-Haro objects. These are luminous regions that form when jets from growing newborn stars crash into the gas and dust around the star.
The long, narrow object that is oriented horizontally in this corner is HH 797. Upon close inspection, this source is revealed to be two protostars with nearly parallel outflows. Just to the right of HH 797 is the propeller-shaped source HH 211. It features both narrow jets and broader outflows.
The data used to create this image come from the Webb observing program #4866 (PIs: K. Luhman, C. Alves de Oliveira). The aims of this program are to study the lowest-mass objects created through the star-formation process, as described here; to understand how the populations of planetary-mass objects like brown dwarfs vary between star-forming regions; and to probe the origins of the hydrocarbon feature in the lowest-mass brown dwarfs.
Webb is an international partnership between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).
Release Date: Sept. 15, 2026
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