Astronomers have noted a planet-like object in a system of failed stars that is closest to the Sun.
arXiv – Astronomy & Astrophysics Letter in Press
Brown dwarf is a star that is smaller than a planet and has a mass equivalent to less than one-tenth of the Sun’s mass. Such stars are not able to burn hydrogen in their centers.
Luhman 16AB is the system of two brown dwarfs located about 6.6 light-years away from us. It was discovered earlier this year. Astronomers including Carnegie’s Yuri Beletsky found that both of the objects have a mass between 30 and 50 Jupiter masses. Our Sun has a mass of about 1,000 Jupiter masses.
“The two brown dwarfs are separated by about three times the distance between the Earth and the Sun. 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,” explained Beletsky.
In the present study, scientists used the FORS2 instrument on European Southern Observatory’s (ESO’s) Very Large Telescope at Paranal to image the brown dwarf couple in the best possible conditions, every 5 or 6 days over the period April 14, to June 22, 2013. They made very precise measurements such as about the positions of the two brown dwarfs.
“We have been able to measure the positions of these two objects with a precision of a few milli-arcseconds,” said Henri Boffin of the ESO. “That is like a person in Paris being able to measure the position of someone in New York with a precision of 10 centimeters.”
Astronomers also found tiny displacements of the two objects in their orbits. These deviations appear correlated showing the presence of an object that is planet-like disturbing the motion of two brown dwarfs.
“Further observations are required to confirm the existence of a planet,” concludes Boffin. “But it may well turn out that the closest brown dwarf binary system to the Sun turns out to be a triple system!”
Nearby Failed Stars May Harbor Planet – Carnegie Institution for Science (http://goo.gl/dNcuYR)
H.M.J. Boffin et al. (2013). Possible astrometric discovery of a substellar companion to the closest binary brown dwarf system WISE J104915.57-531906.1 Astronomy & Astrophysics DOI: 10.1051/0004-6361/201322975