There are many cool ways to discover exoplanets, but finding one because it was warping space-time definitely ranks high on that list.
The planet was found in a system called OGLE-2007-BLG-349 about 8,000 light-years from Earth. It was first observed in 2007, and now Hubble has confirmed that it is indeed a planet. What's more, it was found to be orbiting two red dwarf stars about 11 million kilometers (7 million miles) apart.
According to the study, accepted for publication in The Astronomical Journal, the planet’s mass caused the light of the stars to be slightly warped in a phenomenon known as a "microlensing event". The event revealed a planet orbiting the star, but also the presence of a previously unknown second star.
“The exoplanet was observed as a microlensing event in 2007," said lead author David Bennett, from the NASA Goddard Space Flight Center, in a statement. "A detailed analysis revealed a third lensing body in addition to the star and planet that were quite obvious from the data."
The discovery was part of the Optical Gravitational Lensing Experiment (OGLE), a long-standing project that has investigated small gravitational distortions and their causes.
“OGLE has detected over 17,000 microlensing events, but this is the first time such an event has been caused by a circumbinary planetary system,” explains co-author Andrzej Udalski of the University of Warsaw, Poland.
The most successful planet hunter to date is the Kepler Space Telescope, which has discovered thousands of worlds by carefully monitoring the light from stars and waiting for a planet to pass in front of it. Since Kepler can only observe the same star for a limited amount of time, most of the exoplanets discovered like this have a very short orbital period.
This other method could provide a complementary approach to Kepler when it comes to looking for planets further away from their star.
“This discovery suggests we need to rethink our observing strategy when it comes to stellar binary lensing events,” explains co-author Yiannis Tsapras of the Astronomical Calculation Institute in Heidelberg, Germany. “This is an exciting new discovery for microlensing.”