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Kepler telescope shows Einstein was right, again

April 04, 2013|By Geoffrey Mohan
  • An artist's rendering shows light from a red dwarf star being bent by a denser white dwarf.
An artist's rendering shows light from a red dwarf star being bent… (NASA / JPL-Caltech )

Einstein was right about relativity, again.

NASA’s Kepler space telescope has beamed back the latest evidence that light can be bent by gravity, an element of the theory of general relativity.

It’s not that astrophysicists expect observations to contradict Albert. But the findings represent the first time the phenomenon has been detected in a binary star system, according to NASA.

In this case, a dead star, known as a white dwarf, bent the light from its partner, a small “red dwarf.”  The density of the much smaller white dwarf is far greater than that of its partner.

"This white dwarf is about the size of Earth but has the mass of the sun," said Phil Muirhead of Caltech, 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."

Generally, Kepler scans for tiny aberrations that might indicate a planet has crossed paths with a red star. Muirhead and his team were looking at data from a target called KOI-256, and thought they had seen a large planet transiting the red dwarf.

"We saw what appeared to be huge dips in the light from the star, and suspected it was from a giant planet, roughly the size of Jupiter, passing in front," said Muirhead.

Using the Hale Telescope at Palomar Observatory in San Diego County, the team discovered that the red dwarf was wobbling in a way that was too extreme to be caused by the tug of a planet. They concluded that a massive white dwarf was passing behind the red dwarf. Their suspicions were confirmed by ultraviolet measurements of KOI-256 taken by the Galaxy Evolution Explorer (GALEX).

The team took another look at Kepler data, finding that when the white dwarf passed in front of its partner star, its gravity caused the starlight to bend and brighten.

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

Light bending is not novel to astronomical observation. One effect of this phenomenon is known as gravitational lensing, a process in which light warping around a galaxy is magnified. The phenomenon has been helpful in studying dark matter, dark energy and ancient star-forming galaxies.

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