July 6 (UPI) -- New research suggests the Milky Way is home to more than 100 billion brown dwarfs.
Until now, researchers had only surveyed brown dwarf populations in star clusters within 1,500 light-years of Earth. Brown dwarfs -- an object boasting both planetary and stellar qualities but without the mass to generate fusion -- are relatively faint, making them hard to find in faraway regions of the galaxy.
In 2006, astronomers searched for brown dwarfs among several nearby star clusters, including NGC 1333, located 1,000 light-years away in the constellation of Perseus. The survey revealed a ratio of one brown dwarf for every two stars.
In the latest survey, researchers were surprised to find a similar ratio among RCW 38, a more distant star cluster found in the constellation Vega. RCW 38 is located 5,500 light years from Earth and boasts a larger concentration of high-mass stars. It is quite different in structure and composition than NGC 1333, yet hosts a similar number of brown dwarfs.
"We've found a lot of brown dwarfs in these clusters. And whatever the cluster type, the brown dwarfs are really common," Aleks Scholz, an astronomer at the University of St. Andrews, said in a news release. "Brown dwarfs form alongside stars in clusters, so our work suggests there are a huge number of brown dwarfs out there."
The research -- recently submitted to the journal Monthly Notices of the Royal Astronomical Society -- allowed scientists to develop a more accurate estimate of the galaxy's total brown dwarf population.
Scientists believe the Milky Way hosts a minimum of between between 25 and 100 billion brown dwarfs. It's possible the latest surveys are missing smaller, fainter brown dwarfs.