Free Astronomy Magazine May-June 2025

31 MAY-JUNE 2025 ASTRO PUBLISHING T his near-infrared image of a portion of the Flame Nebula from NASA’s James Webb Space Telescope highlights three low-mass objects, seen in the insets to the right. These objects, which are much colder than protostars, require the sensitivity of Webb’s instruments to detect them. These objects were studied as part of an effort to explore the lowest mass limit of brown dwarfs within the Flame Nebula. The Webb images represent light at wavelengths of 1.15 microns and 1.4 microns (filters F115W and F140M) as blue, 1.82 microns (F182M) as green, 3.6 microns (F360M) as orange, and 4.3 microns (F430M) as red. [NASA, ESA, CSA, STScI, Michael Meyer (University of Michigan)] still relatively warmer and brighter and therefore easier to observe de- spite the obscuring, dense dust and gas that comprises the Flame Nebula in this case. NASA’s James Webb Space Telescope can pierce this dense, dusty region and see the faint infrared glow from young brown dwarfs. A team of as- tronomers used this capability to ex- plore the lowest mass limit of brown dwarfs within the Flame Nebula. The result, they found, were free- floating objects roughly two to three times the mass of Jupiter, al- though they were sensitive 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. With Webb, we’re able to probe the faintest and lowest mass objects,” said lead study author Matthew De Furio of the University of Texas at Austin. The low-mass limit the team sought is set by a process called fragmentation. In this process large molecular clouds, from which both stars and brown dwarfs are born, break apart into smaller and smaller units, or fragments. Fragmentation is highly dependent on several factors with the balance between temperature, thermal pres-