10/12/2024
WEBB • Identifies Tiniest Free-Floating Brown Dwarf
10.12.24
• This image from the NIRCam (Near-Infrared Camera) instrument on NASA’s James Webb Space Telescope shows the central portion of the star cluster IC 348. Astronomers combed the cluster in search of tiny, free-floating brown dwarfs: objects too small to be stars but larger than most planets. They found three brown dwarfs that are less than eight times the mass of Jupiter. The smallest weighs just three to four times Jupiter, challenging theories for star formation.
The wispy curtains filling the image are interstellar material reflecting the light from the cluster’s stars – what is known as a reflection nebula. The material also includes carbon-containing molecules known as polycyclic aromatic hydrocarbons, or PAHs. The bright star closest to the center of the frame is actually a pair of type B stars in a binary system, which are the most massive stars in the cluster. Winds from these stars may help sculpt the large loop seen on the right side of the field of view.
- Brown dwarfs are objects that straddle the dividing line between stars and planets. They form like stars, growing dense enough to collapse under their own gravity, but they never become dense and hot enough to begin fusing hydrogen and turn into a star. At the low end of the scale, some brown dwarfs are comparable with giant planets, weighing just a few times the mass of Jupiter.
•• Credit: NASA, ESA, CSA, STScI
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