Scientists Finally Found Phosphine on a Brown Dwarf. Here’s What That Means for the Search for Extraterrestrial Life

The detection could force astronomers to reconsider their chemical models

Sara Hashemi | Daily Correspondent

October 3, 2025

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For the first time, scientists have detected trace amounts of phosphine—a molecule that, on Earth, is produced only by living beings—in the atmosphere of a brown dwarf.

Wolf 1130C is an ancient brown dwarf located in the constellation Cygnus. Brown dwarfs like Wolf 1130C aren’t planets or stars, though they have features of both. They’re sometimes called “failed stars”: Their formation is star-like, but they lack the mass to continuously fuse hydrogen.

Previous research suggests that brown dwarfs should contain phosphine—which forms when phosphorus combines with hydrogen—given the conditions of their atmospheres. But past observers failed to find a significant amount of the molecule anywhere, puzzling scientists.

Now, in a study published in the journal Science on October 2, scientists report the detection of phosphine on this brown dwarf, thanks to the James Webb Space Telescope’s infrared spectral data.

That doesn’t mean there’s life on Wolf 1130C, the authors stress—and brown dwarfs are not expected to be hospitable for organisms as we know them. Additionally, they hope to better understand the chemistry of phosphine to untangle how the chemical compound may form without the presence of life.

“We have to make sure we do the work of understanding all of the natural processes that can make this molecule before we can rule them out and say there must be a biological source,” says Adam Burgasser, an astrophysicist at the University of California, San Diego, who led the work, to Katrina Miller at the New York Times.

The finding also raises a question: Why hasn’t phosphine been found in the atmosphere of any other brown dwarf? In their work, the authors say the molecule’s presence on Wolf 1130C could be because of the object’s older age and the low abundance of so-called metals—elements heavier than hydrogen and helium—in its atmosphere.

“It may be that in normal conditions, phosphorus is bound up in another molecule, such as phosphorus trioxide,” explains Sam Beiler, a postdoctoral researcher at Trinity College Dublin and study co-author, in a statement. “In the metal-depleted atmosphere of Wolf 1130C, there isn’t enough oxygen to take up the phosphorus, allowing phosphine to form from the abundant hydrogen.”

Or, Wolf 1130C’s white-dwarf companion may have generated the phosphine. A white dwarf is what’s left over when a low-mass star has finished fusing its hydrogen. Wolf’s neighboring white dwarf may have undergone nuclear reactions that created phosphorus, explains Burgasser in the statement.

All this uncertainty could mean that using phosphine as a biosignature is actually flawed—and the results may force researchers to reconsider their chemical models. More research may be needed to understand the molecule before treating it as a possible signal for life, as researchers did when they found it on Venus in 2020.

“The new data really demonstrates that we don’t fully understand PH3 (phosphine) chemical networks in the context of atmospheres, so it is premature to rely on PH3 as a biosignature,” writes Mark S. Marley, a planetary scientist at the University of Arizona who did not participate in the research, in an email to Fionna Samuels at Chemical & Engineering News.

But a better understanding of phosphine and phosphorus synthesis could help researchers better understand the galaxy, too—perhaps yielding insights that could assist in the ongoing search for life outside Earth.

“Understanding phosphine chemistry in the atmospheres of brown dwarfs, where we don’t expect life, is crucial if we hope to use this molecule in the search for life on terrestrial worlds beyond our solar system,” Burgasser says in the statement.

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Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.