Article Posted on : - May 20, 2013

This artist's conception shows Kepler-76b orbiting its host star. Photo: David A. Aguilar (CfA).

CAMBRIDGE, MASSACHUSETTS (BNS): A team at Tel Aviv University and the Harvard-Smithsonian Center for Astrophysics (CfA) has discovered an exoplanet using a new method that relies on Einstein's special theory of relativity.

"Einstein's planet," formally known as Kepler-76b, is a "hot Jupiter" that orbits its star every 1.5 days. Its diameter is about 25 percent larger than Jupiter and it weighs twice as much. It orbits a type F star located about 2,000 light-years from Earth in the constellation Cygnus.

The planet is tidally locked to its star, always showing the same face to it, just as the Moon is tidally locked to Earth. As a result, Kepler-76b broils at a temperature of about 3,600 degrees Fahrenheit.

Although NASA’s Kepler was designed to find transiting planets, this planet was not identified using the transit method. Instead, it was discovered using a technique first proposed by Avi Loeb of the CfA and his colleague Scott Gaudi in 2003, a CfA release said.

The new method looks for three small effects that occur simultaneously as a planet orbits the star. Einstein's "beaming" effect causes the star to brighten as it moves toward us, tugged by the planet, and dim as it moves away. The brightening results from photons "piling up" in energy, as well as light getting focused in the direction of the star's motion due to relativistic effects.

"This is the first time that this aspect of Einstein's theory of relativity has been used to discover a planet," said co-author Tsevi Mazeh of Tel Aviv University.

The team also looked for signs that the star was stretched into a football shape by gravitational tides from the orbiting planet. The star would appear brighter when we observe the "football" from the side, due to more visible surface area, and fainter when viewed end-on. The third small effect was due to starlight reflected by the planet itself.

Once the new planet was identified, it was confirmed by Latham using radial velocity observations gathered by the TRES spectrograph at Whipple Observatory in Arizona, and by Lev Tal-Or (Tel Aviv University) using the SOPHIE spectrograph at the Haute-Provence Observatory in France. A closer look at the Kepler data also showed that the planet transits its star, providing additional confirmation, it said.

Kepler-76b was identified by the BEER algorithm, whose acronym stands for relativistic BEaming, Ellipsoidal, and Reflection/emission modulations. BEER was developed by Professor Tsevi Mazeh and his student, Simchon Faigler, at Tel Aviv University, Israel.