The new discovery was made using the Gemini North Telescope in Hawaii. Special equipment called adaptive optics, which corrects for blurring effects of Earth's atmosphere, made the observations possible.
Eleven similar lightweight binary systems, as the pairs are called, were found in the effort. Together, they provide some new perspective on the formation of stellar systems and how smaller bodies in the universe might form, said the researchers involved in the work.
"We have completed the first adaptive optics-based survey of stars with about 1/10th of the Sun's mass, and we found nature does not discriminate against low-mass stars when it comes to making tight binary pairs," said lead researcher Laird Close of the University of Arizona.
Close will present the findings today at the Brown Dwarfs International Astronomical Union Symposium in Hawaii.
With an estimated mass of 38-70 times that of Jupiter, the newly identified brown dwarf orbits a star known as LHS 2397a. The pair is 46 light-years from Earth.
Often portrayed as "failed stars," brown dwarfs are bigger than giant planets like Jupiter, but their individual masses are less than 8 percent of the Sun's mass (75 Jupiter masses), so they are not massive enough to shine like a star. Brown dwarfs are best viewed in the infrared, as in this study, because surface heat is released as they slowly contract.
The research team looked at 64 low-mass stars that appeared to be solo stars in lower resolution images from the 2MASS all-sky infrared survey. The adaptive optics system, ten times sharper, revealed a dozen companions.
"We find companions to low-mass stars are typically only 4 AU from their primary stars. This is surprisingly close together," said team member Nick Siegler, a University of Arizona graduate student. "More massive binaries have typical separations closer to 30 AU, and many binaries are much wider than this."
The observations "imply strongly that low-mass stars do not have companions that are far from their primaries," Close said.
The detection of brown dwarf companions so close to a star could be an important step toward imaging massive planets around other stars.
The Gemini Observatory is an international cooperative effort including the National Science Foundation.
advertisement
