A team using the James Webb Space Telescope (JWST) spotted the smallest free-floating brown dwarf star ever recorded and two other “failed stars.” They are located in a star cluster that’s only 1,000 light-years from Earth and is not associated with a parent star. The findings were published December 13 in the Astronomical Journal and may help astronomers better determine the boundaries between stars and planets.
[Related: A Jupiter-sized dwarf star burns half as hot as a campfire.]
Failed Stars
Brown dwarfs are celestial bodies that are more massive than planets, but not quite as large as stars. They form the way stars do, growing dense enough to collapse under the weight of their own gravity, but they never become dense and hot enough to start fusing the hydrogen needed to turn into a star. This is why they get the nickname “failed stars.”
The brown dwarf JWST spotted has a mass around eight times that of the planet Jupiter. Meanwhile, the smallest of these stars has a mass around three times that of Jupiter, which challenges current theories about how these types of celestial bodies are formed. Astronomers are using JWST to try and determine what the smallest celestial objects that can form in a star-like manner 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,” study co-author and Pennsylvania State University astronomer Kevin Luhman said in a statement.
Scouring the skies
Luhman and his colleague Catarina Alves de Oliveira began their search with star cluster IC 348. This grouping is only about 1,000 light-years away in the Perseus star-forming region. Star cluster IC 348 is relatively young, at only about 5 million years old. Due to its age, any brown dwarfs present would still be relatively bright in infrared light and be glowing from the heat of their formation.
They imaged the center of the star cluster with…
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