For a decade and a half, astronomers have been on the trail of a galactic mystery.
In 2011, a project that surveyed the Milky Way galaxy for exoplanets — which are planets beyond our solar system — spotted an intriguing signal: They found two objects traveling together through the galaxy, one 2,300 times heavier than its companion. Could it be a rogue planet with a moon, or a small star and orbiting world?
During a recent investigation, researchers poured through observations from the Keck Observatory (located 13,599 feet up in Hawaii) and the European Space Agency's Gaia satellite (which surveyed a whopping 2 billion objects in our galaxy). They think they spotted the curious duo, now located 24,000 light-years away near the center of the galaxy.
But that's not all.
Based on the duo's change in position between 2011 and 2021, the research team gauged that the pair is traveling over 1.3 million miles per hour, or 600 kilometers per second. That's fast enough to propel something beyond the Milky Way's potent gravitational grip.
"If so, the planetary system is destined to traverse intergalactic space many millions of years in the future," NASA wrote.
"If confirmed, the pair sets a record for fastest known exoplanet system," the space agency added. That's nearly twice as fast as our solar system is orbiting around the Milky Way.
The research was recently published in The Astronomical Journal.
The astronomers suspect the hyper-speed duo is a gaseous exoplanet, more massive than Neptune, but not as large as a gas giant like Jupiter.
"We think this is a so-called super-Neptune world orbiting a low-mass star at a distance that would lie between the orbits of Venus and Earth if it were in our solar system," Sean Terry, a researcher at NASA’s Goddard Space Flight Center, said in a statement. “If so, it will be the first planet ever found orbiting a hypervelocity star."
Stay tuned. To confirm this hypervelocity duo is indeed the same duo detected in 2011, researchers will look again in a year or so to see if it's traveling on its expected, high-speed trajectory. If the star continued zooming through space at an unusual speed, they can be confident it's the blazing fast star-planet duo. If the star hasn't moved much, this would suggest the original sighting was indeed a rogue exoplanet, and its exomoon.
