'Einstein's Planet' Discovered with New Method of Finding Exoplanets

Alien planets are being discovered all of the time. But now, researchers are employing new techniques to find them. Most recently, a team has found an exoplanet that uses a new method that relies on Einstein's theory of relativity.

Exoplanets are planets outside of our solar system that orbit distant, alien stars. So far, there are about 800 confirmed exoplanets that have been discovered, and more are being found every day. Usually, there are two main techniques that researchers use in order to detect these planets. The first is radial velocity, which looks for "wobbling" stars. The second is looking for transits, which are dimming stars.

"We are looking for very subtle effects," said team member David Latham in a news release. "We needed high quality measurements of stellar brightness, accurate to a few parts per million."

The new method actually looks for three small effects that occur simultaneously as a planet orbits a star. More specifically, 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.

In addition to watching for this brightening, the researchers also looked for signs that the star was stretched into a football shape by gravitational tides from the orbiting planet. The star itself would actually appear brighter when examined from the "long" side due to more visible surface area. When viewed at its "ends," the star would look fainter. The third effect that the researchers looked for was starlight that was reflected by the planet itself.

So what kind of planet did the researchers find with this new technique? Dubbed "Einstein's planet," the new exoplanet is a hot Jupiter. This superheated planet orbits its star once every 1.5 days and has a diameter that's about 25 percent bigger than Jupiter. Weighing twice as much as the largest planet in our solar system, the new planet is located about 2,000 light years from Earth in the constellation Cygnus.

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

Unfortunately, this new method can't find Earth-sized worlds using current technology. Nonetheless, it does offer astronomers a unique opportunity to find distant planets. Unlike radial velocity searchers, it doesn't require high-precision spectra and unlike transits, it doesn't require a precise alignment of planet and star as seen from Earth. The technique gives astronomers a new tool to use when hunting for far-off exoplanets.

The new findings are published in The Astrophysical Journal.