A team using the incredible James Webb Space Telescope (JWST) has made an incredible discovery! They found the smallest free-floating brown dwarf star ever recorded and two other “failed stars.” But that’s not all—these amazing celestial bodies are located in a star cluster only 1,000 light-years from Earth, and they don’t have a parent star. The groundbreaking findings were published December 13 in the Astronomical Journal, and they could help astronomers determine the boundaries between stars and planets.
[Related: Did you know a Jupiter-sized dwarf star burns half as hot as a campfire?] Find out here.
Failed Stars
Brown dwarfs are massive cosmic objects, bigger than planets and smaller than stars. They form like stars do, getting denser and denser until they finally collapse under their own gravity, but for brown dwarfs, they never get dense and hot enough to start fusing the hydrogen needed to become a true star. That’s why astronomers refer to them as “failed stars.”
The brown dwarf JWST found has a mass around eight times that of Jupiter. But wait—there’s more! The smallest of these stars has a mass around three times that of Jupiter, which challenges current theories about how these celestial bodies form. Using JWST, astronomers hope to figure out what the smallest possible star-like objects really are.
“One basic question you’ll find in every astronomy textbook is, what are the smallest stars? That’s what we’re trying to answer,” said study co-author and Pennsylvania State University astronomer Kevin Luhman in a statement.
Scouring the skies
Luhman and his colleague Catarina Alves de Oliveira began their search with star cluster IC 348. Located only about 1,000 light-years away in the Perseus star-forming region, this star cluster is quite young—only about 5 million years old. Brown dwarfs in this star cluster would still be relatively bright in infrared light and be glowing from the heat of their formation due to their young age.
Using JWST’s Near-Infrared Camera (NIRCam), they imaged the heart of the star cluster to identify any brown dwarf candidates by brightness and color. Then with the microshutter array on JWST’s Near-Infrared Spectrograph (NIRSpec), they looked at the most promising candidates. Thanks to JWST’s sensitivity to infrared light, the team was able to detect fainter objects than other ground-based telescopes.
They narrowed the star cluster down to three possible targets. All of the stars weighed three to eight Jupiter masses and had surface temperatures ranging from 1,500 to 2,800 degrees Fahrenheit. According to the team’s computer models, the smallest target was only three to four times the size of Jupiter and may provide valuable insights into the star formation process.
[Related: Did you know two tiny stars can fit into an orbit smaller than our sun?] Find out more here.
“It’s pretty easy for current models to make giant planets in a disk around a star,” said study co-author and European Space Agency (ESA) astronomer Catarina Alves de Oliveira of ESA in a statement.
