In a surprising twist in the quest for the elusive Planet 9, a team of citizen scientists has stumbled upon a cosmic phenomenon that challenges our understanding of the universe. Rather than discovering the hypothetical planet at the edge of our Solar System, they identified an object moving at such a breakneck speed that it will one day break free from the gravitational pull of the Milky Way. This object is the fastest of its kind ever observed.
The journey of this discovery began with contributors from the Backyard Worlds: Planet 9 project—Martin Kabatnik, Thomas P. Bickle, and Dan Caselden—who first noticed the object while analyzing data from NASA’s Wide-field Infrared Survey Explorer (WISE) mission. This mission, which meticulously mapped the sky in infrared, has been a treasure trove for amateur astronomers. Among the 4,000 brown dwarfs unearthed through this program, none have matched the velocity of this newfound object, which is estimated to be hurtling through space at an astonishing speed of 1.6 million kilometers (1 million miles) per hour.
“I can’t describe the level of excitement,” he said. “When I first saw how fast it was moving, I was convinced it must have been reported already,” said Martin Kabatnik from Nuremberg, Germany, co-author of the paper.
The WISE mission, which concluded in 2011, continues to yield new insights even in its retirement, thanks to citizen scientists who meticulously sift through its data. This particular object, cataloged as CWISE J124909.08+362116.0, is believed to be either a brown dwarf or a very low-mass star. What makes it truly extraordinary is its speed, which is so immense that it is destined to eventually escape our galaxy.
But what could propel a brown dwarf to such incredible speeds? The research team has proposed two possible scenarios. The first involves a binary system where the object is paired with a white dwarf. In this scenario, the white dwarf siphoned enough material to trigger a supernova, sending CWISE J1249 careening through space at an unprecedented velocity.
The second theory suggests that the object originated in a dense globular cluster, where it encountered a pair of binary black holes. The gravitational interaction from this encounter could have catapulted the object out of the cluster and eventually out of the Milky Way.
“When a star encounters a black hole binary, the complex dynamics of this three-body interaction can toss that star right out of the globular cluster,” explained Kyle Kremer, an incoming assistant professor at UC San Diego’s Department of Astronomy and Astrophysics.
Adding another layer of intrigue, the object appears to have an unusual chemical composition, with few heavy elements compared to other stars and brown dwarfs. This suggests that it could be among the oldest objects in the Milky Way.