A strange, fast-moving object is baffling astronomers. Hurtling toward the heart of our galaxy at a blistering 2 million kilometers per hour, this enigmatic body—dubbed CWISE J1249+3621—is challenging our understanding of high-velocity stars and brown dwarfs. What could send such a peculiar object on such a cosmic joyride? Astronomers have some intriguing theories.
What is CWISE J1249+3621?
Occasionally, the universe delivers a mystery that captures the imagination of scientists and enthusiasts alike. This time, it’s CWISE J1249+3621, a celestial oddity located roughly 400 light-years from Earth. With a mass about 8% of the Sun’s, or 80 times that of Jupiter, it straddles the ambiguous boundary between a brown dwarf—often called a “failed star”—and a low-mass star.
The object was discovered as part of the Backyard Worlds: Planet 9 project, a citizen science initiative that uses data from NASA’s Wide-field Infrared Survey Explorer (WISE) to locate faint, moving celestial bodies near our Sun. While its mass and classification are already intriguing, it’s the object’s speed and trajectory that are truly astonishing.
Racing through the galaxy
Astronomers estimate that CWISE J1249+3621 is traveling fast enough to escape the gravitational pull of the Milky Way, placing it among the elusive class of hypervelocity stars. As Adam Burgasser, lead researcher at the University of California, explains, “This object’s speed and trajectory make it unique. Most hypervelocity stars are located thousands of light-years from the Sun, while this one is surprisingly close—only 400 light-years away.”
What’s more, its chemical composition appears unusual, according to early atmospheric analyses. These findings could provide critical clues about its origin and journey. For astronomers, CWISE J1249+3621 is not just an oddity but a potential gateway to better understanding brown dwarfs and high-velocity objects in the outer regions of the Milky Way.
Four theories about its origin
What could propel this cosmic sprinter to such dizzying speeds? Astronomers are considering four main possibilities, each more fascinating than the last.
1. Ejected by Sagittarius A*
The most widely accepted explanation is that Sagittarius A*, the supermassive black hole at the center of the Milky Way, ejected the object. This mechanism has been used to explain other hypervelocity stars, where a close encounter with the black hole’s immense gravitational force flings objects outward at incredible speeds. But here’s the twist: CWISE J1249+3621 isn’t moving outward—it’s heading toward the galactic center, raising questions about whether it’s on a return path.
2. Escaping a “cosmic vampire”
Another possibility involves a dramatic escape from a binary system. Astronomers theorize that CWISE J1249+3621 may have once orbited a white dwarf, a stellar remnant known for siphoning material from its companion in a process likened to vampirism. Such a system could culminate in a cosmic explosion, destroying the white dwarf and launching its companion—CWISE J1249+3621—at high velocity.
3. Thrown from a globular cluster
A third scenario suggests the object was ejected from a globular cluster, a dense collection of stars, due to dynamic interactions with black holes residing at the cluster’s core. Recent simulations support this possibility, showing that these ejections could happen multiple times over the Milky Way’s lifespan. If correct, this theory situates CWISE J1249+3621 within a fascinating context of stellar dynamics and gravitational chaos.
4. An intergalactic intruder
The final and most speculative theory is that CWISE J1249+3621 originated outside the Milky Way and is merely passing through. However, its near-perfect orbital alignment with the Milky Way’s plane makes this explanation less likely. As Burgasser puts it, “The orbit is what makes this object so remarkable—it moves in and out of the Milky Way’s center almost perfectly along the galactic plane. Most hypervelocity stars have far more chaotic or tilted orbits. This might be a key clue to its true origin.”
A new frontier in stellar research
CWISE J1249+3621 represents more than just a curiosity; it opens up new avenues for studying brown dwarfs and other stellar objects that exist in the outer reaches of the galaxy, from the galactic halo to distant globular clusters. Its classification as the lowest-mass high-velocity star ever discovered adds further weight to the discovery. As one astronomer noted, “The processes behind these hypervelocity stars clearly affect both high-mass and low-mass objects, expanding the scope of our research.”
While the mystery of CWISE J1249+3621 may take years to unravel, one thing is certain: the cosmos never ceases to amaze. Whether flung by a black hole, fleeing a stellar vampire, or traversing intergalactic space, this enigmatic traveler reminds us just how little we still know about the dynamics of our galaxy.