Star cluster NGC 1333 contains many brown dwarfs
NASA/CXC/JPL-Caltech/NOAO/DSS
Astronomers have discovered six new worlds that look like planets but formed like stars. These so-called “rogue worlds” are between five and 15 times the mass of Jupiter, and one of them may even host the beginnings of a miniature solar system.
Ray Jayawardene of Johns Hopkins University in Maryland and his colleagues used the James Webb Space Telescope to discover these strange worlds in the NGC 1333 star cluster. Despite being planet-sized, none of these worlds orbit a star, so they likely formed by the collapse of a cloud of dust and gas, similar to how a star like our Sun is born. These objects, which form like stars but don’t have enough mass to sustain the fusion of hydrogen, are called brown dwarfs, or failed stars.
“In some ways, the most shocking thing is what we didn’t find,” Jayawardene says. “Even though we had the sensitivity to do so, we couldn’t find anything with a mass less than five times that of Jupiter.” This may indicate that brown dwarfs can’t form at lower masses — that is, they are the smallest objects that can form like stars.
From their observations, the researchers found that about 10 percent of NGC1333’s objects are made up of brown dwarfs — a much higher number than expected based on star formation models — and that additional processes, such as turbulence, may be driving the formation of these rogue planets.
One of the brown dwarfs is particularly unusual, with a ring of dust around it that’s the same as what formed the planets in our solar system. At about five times the mass of Jupiter, it’s the smallest such ringed world ever found and could be the start of a strange miniature planetary system around a failed star.
“We’ll see them glowing mostly in the infrared from the tiny worlds around these objects — a very reddish glow — and then they’ll fade away over hundreds of millions of years,” Jayawardene says. As the brown dwarf dims, any planets that form around it will freeze out completely, darkening the entire system, making these worlds less promising for searching for life.
Journal References: Astronomical Journalin press
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