Recently discovered brown dwarf twins, Gliese 229ba and Gliese 229bb. Discovered in 1995, Gliese 229b was the first brown dwarf star ever identified, but until now astronomers thought they were observing one object instead of two. New observations by the European Southern Observatory’s Very Large Telescope in Chile show that the sphere is two brown spheres orbiting closely around each other every 12 days (as indicated by the orange and blue orbital lines). It turns out that they are dwarf stars, and that they are only 16 times their distance apart. between the earth and the moon. A pair of brown dwarfs orbits a cool m-type dwarf every 250 years. (Credit: K. Miller, R. Hurt (California Institute of Technology/IPAC))
Brown dwarfs are thought to be the “Goldilocks” of celestial bodies, being lighter than stars but heavier than gas giants like Jupiter, with a “just right” weight in between.
But something was going on with the first known brown dwarf, Gliese 229B. It was discovered by researchers at the California Institute of Technology. Institute of Palomar Observatory in 1994Astronomers noted that although Gliese 229B weighs about 70 times more than Jupiter, it shines much dimmer considering its mass.
Hundreds of papers have been written about Gliese 229B since its discovery, but the mystery surrounding the discrepancy in its size and brightness remains. Now, two teams of astronomers are explaining the anomaly. Gliese 229B is actually a pair of tightly bound brown dwarfs, about 38 and 34 times heavier than Jupiter.
A pair of brown dwarfs
The brightness levels observed for this pair match what would be expected for two small, dim brown dwarfs in this mass range. According to reports in a diary nature and Astrophysical Journal Letters (AJL). Observation results of the European Southern Observatory very large telescope In Chile, scientists have discovered that two brown dwarf stars orbit each other closely every 12 days.
“Gliese 229B was thought to be a successor to brown dwarfs,” says Jerry W. Xuan, a graduate student at Caltech and an author on the paper. nature stated in the paper and press release. “And now we find that we were wrong about the properties of the objects all along: not one, but two. Until now we have not been able to investigate such close distances.”
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High resolution photo of the new orbit
Rebecca Oppenheimer was a graduate student member of the Caltech team that first discovered Gliese 229B. As the author of the APL report, she is once again excited. That’s because she and her team have once again witnessed a new phenomenon: two brown dwarfs orbiting close to each other.
“I was thrilled to see the first object smaller than a star orbiting another sun,” Oppenheimer, now an astrophysicist at the American Museum of Natural History, said in a press release. “At that time, a cottage industry of people seeking such oddballs began, but they remained a mystery for decades.”
Through newer, higher-resolution telescopes, both teams got a clearer picture of what the double brown dwarf was doing. How and why twins are formed is still a mystery. Some theories suggest that the brown dwarf pair was seeded from material surrounding a forming star.
This discovery also leads to the question of whether there are more such twins in the universe. Astronomers will continue to point ever more powerful instruments into the sky to answer these questions.
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Before joining Discover Magazine, Paul spent more than 20 years as a science journalist, specializing in U.S. life sciences policy and global scientist career issues. He started his career in newspapers but switched to scientific magazines. His research has appeared in publications such as Science News, Science, Nature, and Scientific American.
