Webb Finds the Smallest "Failed Stars" Ever Seen
In a cloud of gas and dust about 1,000 light-years away, in the constellation of Perseus, new stars are being born. The James Webb Space Telescope has just taken its most detailed picture yet of that stellar nursery — and in it, astronomers have found the smallest "failed stars" ever seen: objects just twice the mass of Jupiter.
The new image of the nebula IC 348 was released on 9 November 2026. It is an ultra-wide-field composite made from many images taken by Webb's NIRCam camera, spanning about one billion pixels in total, and it shows more than a thousand new stars and protostars in various stages of formation. The image comes from ESA/Webb, NASA and the Canadian Space Agency, with the work led by Kevin Luhman of Penn State University and Catarina Alves de Oliveira of the European Space Agency.
What is a failed star?
A brown dwarf is an object that formed like a star — from a collapsing cloud of gas — but never grew massive enough to ignite the nuclear fusion that makes a star shine. It glows faintly from the heat of its formation, then slowly cools. Astronomers call them failed stars, and they sit in the gap between the smallest true stars and the largest planets.
Theory used to set a lower limit for these objects at about 13 times the mass of Jupiter: below that, an object should not be able to form on its own like a star at all. Webb has now broken that limit twice. In 2023, searching IC 348, the same team found free-floating objects less than eight times Jupiter's mass, including a then-record holder of just three to four Jupiter masses. The new image and spectroscopic follow-up work have broken the record again: objects of just two Jupiter masses, confirmed by their spectra to be only about 0.19% of the mass of the Sun. One pair of these objects together has a mass of just two Jupiters, making it consistent with being the lightest brown dwarf known — and one of the objects even appears to possess a disc of material around it, like the discs that form planets around young stars.
Why it matters
These objects should not exist, according to the old picture — yet there they are, glowing faintly in infrared light that only Webb can see. Their existence means the process that makes stars can produce objects far smaller than anyone expected, blurring the line between stars and planets. The faintest objects in the image glow like brown dwarfs but have the mass of giant planets, and astronomers say they could represent a new class of object altogether.
For students, IC 348 is a perfect picture of how science moves: a theory sets a limit, a better telescope looks, and the limit turns out to be wrong. The brightest blue stars dominate the light in the image, but they are far outnumbered by the faint, red, low-mass objects — a reminder that in astronomy, as in a classroom, the loudest voices are not always the most numerous.
If your child looks up at the night sky and wonders how stars are born — or what separates a star from a planet — a first lesson in physics or astronomy can take them from gravity and gas clouds to the telescope that is rewriting the textbooks right now. Book your first lesson
Sources:
- Big Think, "In a big star-forming nebula, JWST finds the smallest failed stars", 9 November 2026: https://bigthink.com/starts-with-a-bang/star-forming-nebula-jwst-smallest-failed-stars/
- Luhman and Alves de Oliveira, Astrophysical Journal Letters (2025), spectroscopic confirmation of the IC 348 brown dwarfs
London Tutors — post your tutoring request and we will match you with a verified tutor.