Hubble Finds Planet Orbiting Pair of Stars

Posted September 24, 2016

The circumbinary planet is located 8,000 light years from Earth toward the center of the Milky Way.

As microlensing events are, by their nature, one-offs, astronomers needed another way to confirm the nature of OGLE-2007-BLG-349 and Hubble has been used to zoom in on the star system that triggered the 2007 brightening. This distance is 14 times the diameter of the moon's orbit around Earth, according to NASA. The giant exoplanet orbits the stars at a distance of 300 million miles.

They were not able to examine closely at the time, but to get a better view, the team made a decision to use the Hubble Space Telescope to examine deep space, which then revealed the other star.

The system, OGLE-2007-BLG-349 (or as I choose to christen it: "New Tatooine"), is 8,000 light-years away from Earth. When it was first discovered by an global collaboration of researchers in 2007, they detected only one star and a planet, but a detailed analysis also revealed a third body that astronomers could not definitively identify at the time.

A two-planet single-star model is not possible. This is the first time a binary system plus single exoplanet has been discovered through microlensing.

"So the model with two stars and one planet is the only one consistent with the Hubble data", Dr. Bennett said in the NASA announcement. The exoplanet which falls under a category called circumbinary planet was found by observing an astronomical phenomenon called gravitational microlensing, which was first predicted by Albert Einstein. This magnification reveals qualities of the foreground star, including the presence of orbiting planets. It completes one orbit around the binary every seven years. Now, astronomers have actually confirmed the said unique star system. While data from the Kepler Space Telescope is more likely to reveal planets that orbit close to their stars, microlensing allows planets to be found at distances far from their host stars. The two stars in this system, which are red dwarfs, or small and low energy stars, are 7 million miles apart from each other.

The system, called OGLE-2007-BLG-349, was originally detected in 2007 by the Optical Gravitational Lensing Experiment (OGLE), a telescope at the Las Campanas Observatory in Chile that searches for and observes microlensing effects from small distortions of spacetime, caused by stars and exoplanets.

"We were helped in the analysis by the nearly flawless alignment of the foreground binary stars with the background star, which greatly magnified the light and allowed us to see the signal of the two stars", he added.

According to Universe Today, with Hubble Telescope's sharp eyesight, astronomers were able to separate the lensing star and the background source star from their neighbors in the very crowded star field. Microlensing has already been observed as early as 2007, however, this is the first time a planet that orbits two Suns, also known as "circumbinary" planet was confirmed by following the microlensing or light-bending activity. The brightness likewise characterizes closely orbiting pair of red dwarf stars that are less massive and fainter than the sun.