Lonely Planet Unattached to a Star Found in Deep Space

PHOTO: In this illustration the object, called WISEA J114724.10-204021.3, is thought to be an exceptionally low-mass "brown dwarf," which is a star that lacked enough mass to burn nuclear fuel and glow like a star. PlayNASA/JPL-Caltech
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Our galaxy is believed to be home to billions of free-floating planets with mysterious origins, unattached to a star, and now astronomers have zeroed in a newly detected planetary-mass object that could help give new insights into the formation of these worlds.

NASA has theorized the objects could be planets ejected from solar systems or they could be lightweight stars known as brown dwarfs, which form alone in space like stars but without the mass to fuse atoms at their cores or shine.

The space agency's Wide-field Infrared Survey Explorer, WISE, and the Two Micron All Sky Survey, or 2MASS, detected the free-floating, planetary-mass object within a young star family, according to a NASA blog post. The discovery, which will be published in The Astrophysical Journal, was found by looking at photos taken of the entire sky by the instruments a decade ago.

The free-floating worlds are of particular interest to scientists since they lack host stars, making it easier to look at the planet’s composition and weather.

It’s believed the object is young by astronomical standards -- about 10 million years old. Since planets take at least 10 million years to form, astronomers believe it’s unlikely this object would have been ejected from a solar system, leading them to theorize it originated as a brown dwarf.

We've already learned this world -- known officially as WISA 1147 -- is believed to be heavy: Scientists say it's between five and ten times the mass of Jupiter, the largest planet in our solar system. For an object to ignite and become a star, scientists have calculated that the critical mass would need to be about 100 times the mass of Jupiter. Our sun is about 1,000 times the mass of Jupiter.