SPHEREx spacecraft reveals chemical makeup of dozens of brown dwarfs

By the Everything Space news desk · 19 Oct 2026 · written from the sources below

Image: Space.com

New infrared observations show these starless, planet-like bodies have complex, varied atmospheres that current models struggle to explain.

Astronomers using NASA's SPHEREx spacecraft have taken a detailed look at brown dwarfs, the so-called failed stars that are too massive to be planets but too light to sustain the hydrogen fusion that powers true stars. The research, led by Zafar Rustamkulov of Caltech, examined 37 nearby brown dwarfs across a wide range of temperatures, from scorching hot to frigid.

Brown dwarfs form like stars, collapsing out of clouds of gas and dust, but never gain enough mass to ignite full fusion. Because they drift through space without a parent star, they emit very little light, making them difficult to study from the ground. SPHEREx can detect wavelengths of light blocked by water vapor in Earth's atmosphere, giving it an advantage over ground-based telescopes.

Analyzing light across 102 wavelengths, the team found that brown dwarf atmospheres are rich in water, carbon dioxide, carbon monoxide and methane, chemical signatures that shift depending on each object's temperature. The spacecraft also caught some brown dwarfs undergoing a dramatic transition stage, where their clouds appear to be clearing out, leaving atmospheres dominated by methane.

Despite gathering this new chemical data, researchers say current atmospheric models fail to fully capture the cloud transitions they observed. Team member J. Davy Kirkpatrick noted that no two brown dwarfs look alike, even when they share similar temperatures, complicating efforts to build a consistent theoretical picture.

The study covered only three dozen of the objects, with researchers saying thousands more brown dwarfs captured by SPHEREx remain to be analyzed. The findings were published in The Astrophysical Journal.

Written in Everything Space’s own words by our news-desk model from the sources above, and checked against them in code: every number in this report appears in its sources, and no sentence is copied from them.