Scientists have been observing a brown dwarf for decades, and now they have discovered that it is actually two dwarfs circling each other.
Gliese 229B, the first brown dwarf discovered three decades ago, has been a significant object of interest.
Brown dwarfs are perplexing objects and are perceived to be failed stars because they are lighter than stars but heavier than planets. This isn’t the first time a pair of brown dwarfs have been found circling each other, but this does provide insight into brown dwarf pairings.
The twin brown dwarfs
After scientists using the Very Large Telescope in Chile observed Gliese 229B and saw that it was too dim for its mass, they took a closer look and found that two brown dwarfs were circling each other. The pair orbit each other every 12 days, which is much faster than even the moon’s orbit.
Study co-author Rebecca Oppenheimer with the American Museum of Natural History said, “It shows you how weird the universe is and how different solar systems are from our own.”
Gliese 229B was studied for years as the perfect example of what a brown dwarf is, and it turns out that scientists were fundamentally wrong about it in the first place.
“Gliese 229B was considered the poster-child brown dwarf,” said Jerry W. Xuan, a graduate student and lead author of the study. “And now we know we were wrong all along about the nature of the object. It’s not one but two. We just weren’t able to probe separations this close until now.”
Considering their close orbit and proximity to each other, it raises questions about the nature of brown dwarfs and how they tend to orbit each other. The fact that it took 30 years for the Gliese 229B duo to be discovered suggests that finding similar duos could end up being the norm.
“This discovery that Gliese 229B is binary not only resolves the recent tension observed between its mass and luminosity but also significantly deepens our understanding of brown dwarfs, which straddle the line between stars and giant planets,” said Dimitri Mawet, the David Morrisroe Professor of Astronomy.
This discovery was made possible thanks to the advancement of technology as a whole, particularly in astronomy. Gliese 229B was the first brown dwarf ever discovered, but no one knew it had a twin until three decades later. This was due to its close orbit, but discoveries like this are possible with new observation technology like the Very Large Telescope in Chile.
Shri Kulkarni, the Caltech graduate student who helped discover Gliese 229B, said, “It is so nice to see that almost 30 years later, there has been a new development. Now, this binary system stuns again.”
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