December 17, 2013
Possible Planet Discovered In Nearby Brown Dwarf Binary System
redOrbit Staff & Wire Reports - Your Universe Online
Analysis of the two brown dwarfs located closest to the sun suggests that there could actually be a third, previously undetected planetary-mass object, according to research published as a letter to the editor in the journal Astronomy & Astrophysics.Brown dwarfs, which are failed stars that have a mass of less than 8 percent the mass of the sun, are not massive enough to burn hydrogen in their centers. The system at the center of the newly-published research, Luhman 16AB, was located earlier this year and is less than seven light years away, the researchers said in a statement.
Following the system’s discovery, Yuri Beletsky of the Carnegie Institution of Science and his colleagues used multiple telescopes in order to study the brown dwarf pair. After conducting two months of observations and data analysis, they found that both objects possess a mass of between 30 and 50 Jupiter masses. For reference, the Sun possesses a mass of approximately 1,000 Jupiter masses.
“The two brown dwarfs are separated by about three times the distance between the Earth and the Sun,” Beletsky explained. “Binary brown dwarf systems are gravitationally bound and orbit about each other. Because these two dwarfs have so little mass, they take about 20 years to complete one orbit.”
He and his associates used the Focal Reducer and Low Dispersion Spectrograph (FORS2) instrument on the European Southern Observatory’s (ESO) Very Large Telescope to image the two failed stars under optimal conditions every five or six day from April 14 to June 22.
“Because of the instrument enabled the observers to make very precise measurements, the scientists were already able to detect tiny displacements of the two objects in their orbit during only this the two-month period,” the Institution said. “The astronomers were able to measure the positions of the two brown dwarfs with ten times better accuracy than before and thereby detect even small perturbations of their orbit.”
“We have been able to measure the positions of these two objects with a precision of a few milli-arcseconds,” added the ESO’s Henri Boffin. “That is like a person in Paris being able to measure the position of someone in New York with a precision of 10 centimeters.”
The measurements that Boffin, Beletsky and their colleagues collected were so fine that they were able to notice exceptionally small deviations from the anticipated motion of the two brown dwarfs around one another. Furthermore, there appeared to be a correlation between the two which indicates that a third object is disturbing the motions of at least one of them.
They believe that this entity is a planetary-mass object with an orbital period lasting between 2 and 12 months. Boffin said that further research will be needed to confirm the existence of a planet, but that the dwarf binary system closest to the sun could actually turn out to be a triple system.