What you're looking at here is the first direct imaging of a planet orbiting a pair of stars. Trouble is, the planet is so large — about 12 to 14 times the size of Jupiter — that it might actually be a failed star, a so-called brown dwarf. But for now, the astronomers are cool with calling the massive object a planet.


The picture was taken late last year by Philippe Delorme of the Joseph Fourier University in Grenoble using a telescope in Chile. The planet, called 2MASS0103(AB)b, is indicated by the green arrow, while the blue circle at top right shows where the object would have been expected were it simply a background object.

The planet (or whatever it is) orbits at a distance of around 12.5 billion kilometers, which means it probably arose from a disc of dust surrounding the stars. But it did not form the normal way.


New Scientist explains:

"It's either one of the most massive planets you can form or the lowest-mass star you can imagine," says Delorme. If it is a planet, it must have formed via gravitational instability, in which clumps in the dust disc quickly collapse into planets. It is too large in relation to the stars to have been made by core accretion, a more widely accepted model in which planets grow via slow accumulation. Delorme notes that the current mass-based dividing line between planets and failed stars "is more of a working definition, as it is easier to measure the mass of an object than its past formation history". His team is now analysing the object's light spectrum to learn more about its atmosphere. Figuring out the chemical makeup of 2MASS0103(AB)b could confirm the object as a Jupiter-like planet, lending weight to the instability model. Or it could reveal that the object is in fact a rare type of brown dwarf that was born together with the binary pair. All three would have formed when turbulence inside an embryonic star caused it to break into pieces. That in turn might be crucial to properly identifying such bodies in the future.

These findings are not yet published, but you can still check out the study for yourself (which was accepted by the A&A for formal review).

Image: ESO.