According to NASA, astronomers have discovered what is possibly a "scrawny" star speeding through the Milky Way with a planet in tow. If the system is confirmed, it would set a new record for the fastest-moving exoplanet system ever spotted, the agency said.
The planetary system is reportedly thought to be moving at least 1.2 million miles per hour, nearly twice as fast as our solar system.
Sean Terry, a postdoctoral researcher at the University of Maryland, College Park and NASA's Goddard Space Flight Center in Greenbelt, Maryland, published a paper describing the findings in the The Astronomical Journal.
"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," Terry said.
NASA said that since the star is so weak, the planet would be well outside its habitable zone, but Terry stated that if the planet is confirmed, it would be the first planet ever found orbiting a hypervelocity star.
The pair of objects was first sighted indirectly in 2011 by chance, according to NASA. The agency said a team of scientists was going through data from Microlensing Observations in Astrophysics (MOA), a collaborative project on a microlensing survey, looking for evidence of planets outside of our solar system, known as exoplanets.
"Microlensing" happens when an object with mass "warps the fabric of space-time", NASA described. When an object appears to drift near a star, light from the star curves as it travels through the warped space near the object. If the object is especially close, the warping of the light can act like a natural lens, amplifying the background star's light, NASA said.
The agency said in this instance, microlensing signals revealed a pair of "celestial bodies". Scientists say one of the objects is about 2,300 times heavier than the other, but it will be difficult to determine the exact mass of each until scientists are able to figure out how far they are from Earth.
In 2011, the team reportedly suspected the objects were either a star with about the 20% the mass of our sun and a planet about 29 times heavier than Earth, or a closer "rogue" planet about four times the mass of Jupiter with a moon smaller than Earth.
To determine which explanation was more likely, astronomers reportedly looked through data from the Keck Observatory in Hawaii and the European Space Agency (ESA)'s Gaia satellite.
If the objects were a rogue planet and a moon, they would be effectively invisible, said NASA, but if they were a star and a planet, scientists might be able to find the star. The astronomers reportedly found a "strong suspect" about 24,000 light-years away, within the Milky Way's "galactic bulge", or the center where stars are more densely packed. The scientists reportedly calculated the star's speed by comparing its location in 2011 and 2021.
If the star is moving away from Earth, NASA says it could be moving even faster than estimated. The agency said the system's true speed could possibly be enough to escape the galaxy and launch into intergalactic space.
"To be certain the newly identified star is part of the system that caused the 2011 signal, we'd like to look again in another year and see if it moves the right amount and in the right direction to confirm it came from the point where we detected the signal," said David Bennett, a senior research scientist at the University of Maryland, College Park and NASA Goddard, who co-authored the new paper and led the original study in 2011.
NASA said its upcoming Nancy Grace Roman Space Telescope could help shed more light on how common planets are around such fast-moving stars, and may offer clues as to how the systems are accelerated.