Light-bending planet found orbiting two stars

Astronomers have been able to discover an exoplanet orbiting two suns by observing how its mass warps spacetime.

Artist's impression of the exoplanet that was discovered orbiting two stars. The planet was initially detected using a technique that measures its effect on spacetime, and then confirmed using the Hubble Space Telescope. NASA, ESA, and G. Bacon (STScI)

A planet orbiting two red dwarf stars has been confirmed by astronomers who initially detected it by observing its effect on spacetime.

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Data from the Hubble Space Telescope has confirmed the planet does indeed exist, following its initial detection in 2007 using a technique called gravitational microlensing.

This method looks for the warping of spacetime and the consequent bending of light caused by massive objects in space, as predicted by Einstein’s general theory of relativity.

It is the first time a planet orbiting two stars has been detected using this method.

The planet is part of the system OGLE-2007-BLG-349, located about 8,000 lightyears away.

It has a similar mass to Saturn and orbits its stars at a distance of about 480 million kilometres. The two red dwarf stars are just 11 million kilometres apart.

Its discovery was part of the Optical Gravitational Lensing Experiment at the University of Warsaw in Poland.

The project is chiefly concerned with using gravitational microlensing to search for dark matter, but has also discovered several exoplanets in addition.

The double star system was detected using this method, but the study also showed evidence of a third body that could not be accounted for.

Data from the Hubble Space Telescope has now confirmed that the third object is in fact a planet orbiting the two stars.

“This discovery suggests we need to rethink our observing strategy when it comes to stellar binary lensing events,” says Yiannis Tsapras, co-author of the study from the Astronomisches Rechen-Institut in Heidelberg, Germany.

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“This is an exciting new discovery for microlensing”.