Gravity-Bending Find Leads to Kepler Meeting Einstein

NASA's Kepler space telescope witnesses the effects of a dead star bending the light of its companion star.

NASA's Kepler space telescope has witnessed the effects of a dead star bending the light of its companion star. The findings are among the first detections of this phenomenon — a result of Einstein's general theory of relativity — in binary, or double, star systems.

The dead star, called a white dwarf, is the burnt-out core of what used to be a star like Earth’s sun. It is locked in an orbiting dance with its partner, a small “red dwarf" star. While the tiny white dwarf is physically smaller than the red dwarf, it is more massive. This artist's concept above depicts a white dwarf crossing in front of a small, red star. The white dwarf's gravity is so great it bends and magnifies light from the red star.

"This white dwarf is about the size of Earth but has the mass of the sun,” said Phil Muirhead of the California Institute of Technology, Pasadena, lead author of the findings to be published April 20 in the Astrophysical Journal. “It's so hefty that the red dwarf, though larger in physical size, is circling around the white dwarf.”

Scientists from Germany, Canada and India joined American colleagues to author the study.

Kepler's primary job is to scan stars in search of orbiting planets. As the planets pass by, they block the starlight by miniscule amounts, which Kepler's sensitive detectors can see.

"The technique is equivalent to spotting a flea on a light bulb 3,000 miles away [4,828 kilometers], roughly the distance from Los Angeles to New York City," said Avi Shporer, a co-author of the study, also of Caltech.

“Only Kepler could detect this tiny, tiny effect,” said Doug Hudgins, the Kepler program scientist at NASA headquarters. “But with this detection, we are witnessing Einstein's general theory of relativity at play in a far-flung star system.”