In 1995, astronomers confirmed the discovery for the first time of a brown dwarf, a body too small to be a star and too big to be a planet – sort of a celestial tweener.
- Researchers now have taken a fresh look at that brown dwarf and learned that it actually is not a single brown dwarf but rather two of them orbiting astonishingly close to each other while circling a small star.
- This was documented in two new studies using telescopes in Chile and Hawaii.
- So the brown dwarf that three decades ago was named Gliese 229B is now recognized as Gliese 229Ba, with a mass 38 times greater than our solar system’s largest planet Jupiter, and Gliese 229Bb, with a mass 34 greater than Jupiter.
- They are located 19 light-years from our solar system – rather close in cosmic terms – in the constellation Lepus. Binary brown dwarfs are a rarity.
- These two brown dwarfs are gravitationally locked to each other in what is called a binary system, an arrangement commonly observed among stars.
- These two orbit each other every 12 days at a distance of only 16 times the separation between Earth and the moon.
- Brown dwarfs are neither a star nor a planet, but something in between. They could be considered wannabe stars that during their formative stages did not reach the mass necessary to ignite nuclear fusion at their core like a star. But they are more massive than the biggest planets.
- They are formally defined as objects that can burn a heavy form of hydrogen, called deuterium, but not the most common basic form of hydrogen. In practice, this means they range in mass from approximately 13 to 81 times the mass of Jupiter.
- Because they can’t fuse hydrogen, they can’t ignite the fusion channels that power most stars. This causes them to just glow dimly as they cool down.
