Einstein’s theory aids planet-hunters
24 Jun 2013 by hjcmtbbcwq.d hjcmtbbcwq.d
A team of astrophysicists have discovered an exoplanet using a new method that relies on Einstein’s special theory of relativity.
The exoplanet known as Kepler-76b is like a hotter, larger Jupiter. It orbits a star located about 2000 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 co-author Tsevi Mazeh from Tel Aviv University.
Kepler-76b was identified by the BEER algorithm, which stands for relativistic BEaming, Ellipsoidal, and Reflection/emission modulations.
To find Kepler-76, the team looked for three small effects that all occur at the same time as the planet orbits the star. Einstein’s ‘beaming’ effect causes the star to brighten as it moves towards 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.
The team also looked for signs that the star was stretched into a football shape by gravitational tides from the orbiting planet. The star appears brighter to viewers on Earth when the ‘football’ is observed from the side, due to more visible surface area.
The third effect comes from the starlight reflected by the planet.
“We were looking for very subtle effects. We needed high quality measurements of stellar brightnesses, accurate to a few parts per million,” said team member David Latham from the Havard-Smithsonian Center (CfA).
Once the new planet was identified, it was confirmed using radial velocity observations gathered by the TRES spectrograph at Whipple Observatory in Arizona, and using the SOPHIE spectrograph at the Haute-Provence Observatory in France.
The new method can’t find Earth-size worlds using the current technology, but does offer astronomers a unique discovery opportunity because it doesn’t require high-precision spectra, unlike radial velocity searches. And unlike transits, it doesn’t require a precise alignment of planet and star as seen from Earth.
“Each planet-hunting technique has its strengths and weaknesses. And each novel technique we add to the arsenal allows us to probe planets in new regimes,” said Avi Loeb from the CfA who first proposed the technique in 2003 with colleague Scott Gaudi.
The paper announcing this Kepler-76b’s discovery has been accepted for publication in The Astrophysical Journal.
