NASA’s James Webb Space Telescope (JWST) has made a groundbreaking discovery in the Flame Nebula, a star-forming region approximately 1,400 light-years from Earth.
Using its advanced infrared capabilities, JWST has identified a population of free-floating brown dwarfs, some of which are as small as two to three times the mass of Jupiter.
This discovery challenges previous assumptions about the lower mass limits of star formation and pushes the boundaries of substellar object research.
Probing the Birthplace of Brown Dwarfs
The Flame Nebula is a dense, dusty molecular cloud where young stars are actively forming. Among the many celestial objects residing in this region are brown dwarfs, which are sometimes referred to as “failed stars” because they lack the necessary mass to sustain hydrogen fusion like traditional stars.
Over time, these objects cool and dim, making them incredibly difficult to detect with conventional telescopes.However, JWST’s powerful infrared vision has enabled astronomers to peer through the thick dust and capture the faint glow of young brown dwarfs.
The research team, led by Matthew De Furio of the University of Texas at Austin, set out to explore the fundamental low-mass limit of star and brown dwarf formation. Their findings revealed that some of the free-floating objects in the Flame Nebula are only two to three times the mass of Jupiter.
More impressively, JWST’s sensitivity was powerful enough to detect even smaller bodies—down to 0.5 times the mass of Jupiter.
“The goal of this project was to explore the fundamental low-mass limit of the star and brown dwarf formation process,” said De Furio. “With Webb, we’re able to probe the faintest and lowest mass objects.”
A Leap Forward from Hubble’s Observations
While JWST’s findings are revolutionary, they build upon decades of previous research, particularly observations made by the Hubble Space Telescope.
Hubble had already identified candidate brown dwarfs within the Orion Molecular Cloud Complex, which includes the Flame Nebula. However, Hubble lacked the capability to study brown dwarfs at such low masses.
“It’s really difficult to do this work, looking at brown dwarfs down to even ten Jupiter masses, from the ground, especially in regions like this,” De Furio explained. “Having existing Hubble data over the last 30 years or so allowed us to know that this is a really useful star-forming region to target. We needed to have Webb to be able to study this particular science topic.”
Massimo Robberto of the Space Telescope Science Institute described JWST’s impact as a “quantum leap” in understanding substellar objects. Unlike Hubble, which could only hint at these objects, JWST has provided direct evidence of their existence and precise mass measurements.
Are They Planets or Low-Mass Brown Dwarfs?
One of the most intriguing aspects of this discovery is the overlap between planets and extremely low-mass brown dwarfs. Some of these objects border the mass range of giant exoplanets, blurring the line between what constitutes a planet and a failed star.
“There’s a big overlap between the things that could be planets and the things that are very, very low mass brown dwarfs,” said Michael Meyer, an astronomer involved in the study. “And that’s our job in the next five years: to figure out which is which and why.”
To answer this question, the research team plans to use JWST’s spectroscopic instruments to analyze the chemical composition and formation history of these celestial bodies.
By studying the smallest and faintest brown dwarfs ever detected, scientists are now closer than ever to understanding how stars, planets, and brown dwarfs form in the chaotic environments of star-forming regions.
