KOI-3278, a bizarre 'self-lensing' binary star system, discovered in Lyra


KOI-3278 is a bizarre binary star system, located 2,600 light years away in the constellation of Lyra. 

The pair were discovered by a student astronomer at the University of Washington. Doctoral student Ethan Kruse and Eric Agol, an astronomer at the school, made this first-ever discovery of a "self-lensing" binary star system. These were first predicted in 1973, but never seen before. 

"The basic idea is fairly simple. Gravity warps space and time and as light travels toward us it actually gets bent, changes direction. So, any gravitational object -- anything with mass -- acts as a magnifying glass... And instead of getting a dip, now you get a brightening through the gravitational magnification," Agol said

The Kepler Spacecraft was launched in 2009 on a mission to find planets around other worlds. In August 2013, NASA announced it was abandoning the primary mission of the craft after thruster failures. Before that happened, Kepler discovered at least 961 planets orbiting other stars. Data from the observatory is still being examined, and it was in those measurements that KOI-3278 was discovered. 

Although popularly being called an "upside down planet," the term is not quite accurate. Both members of the pair are stars.   

Planets and other bodies orbiting around other stars can block some of the light coming from their companion. Strangely, KOI-3278 creates a lensing effecting, increasing the light reaching the Earth from it's stellar partner. 

"Over 40% of sun-like stars are bound in binary or multistar systems. Stellar remnants in edge-on binary systems can gravitationally magnify their companions, as predicted 40 years ago," researchers wrote in the article announcing the discovery.

The binary pair, KOI-3278, consists of a small white dwarf orbiting around a larger companion once every 88 days. The smaller object is roughly 63 percent as massive as the sun. The stars are located in the constellation Lyra, which is also home to Vega, the brightest star in the constellation. 

When a planet of a star passes in front of a star, it is called a transit. Measuring the amount of light blocked by the orbiting body allows astronomers to determine its size. 

"I found what essentially looked like an upside-down planet. What you normally expect is this dip in brightness, but what you see in this system is basically the exact opposite -- it looks like an anti-transit," said Kruse of the University of Washington. 

Study of the unusual stellar binary may assist in confirming theories of the evolution of these systems, as well as the physics of a white dwarf, a dead star that has used its fuel. White dwarfs can be used to estimate age inside a galazy since they lose energy at a set rate.

Discovery of KOI-3278 was detailed in the journal Science.  

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