May 14, 2013
First New Exoplanets Discovered Using New Method
John P. Millis, Ph.D. for redOrbit.com — Your Universe Online
The field of exoplanet research — the study of planets outside of our solar system — has exploded in the last decade as new instruments have come online that have dramatically increased our ability to find new worlds.
Perhaps the most important player in the game is the Kepler mission. It primarily works by analyzing stars in our galaxy and looking for tiny changes in a star´s brightness. As a planet passes in front of the star, the amount of light we see dips slightly. The amount of the dip and the time it takes the planet to transit helps scientists identify the mass and orbital distance of the planet around the star.
But now a team is using the highly sensitive Kepler data in a new way, and is finding planets that otherwise cannot be seen using the transit method. "We are 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 of the CfA.
The team looks to see subtle changes in the brightness and shape of the star. According to Einstein´s theory of general relativity, as the planet tugs on the star the brightness will increase slightly as it moves towards us, and will dim as it recedes. Meanwhile, this same planetary gravity will cause the planet to bulge slightly. The result is the star would look brighter on the side being stretched. Finally, light from the star could be reflected off of the planet itself.
Applying this new analysis method to the Kepler data, the team was able to identify the first in what is hoped to be a series of new planets. Planet Kepler-76b, now known as Einstein´s planet, is a Jupiter-like planet, but much hotter due to its proximity to its host star — orbiting once every Earth 1.5 days.
"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.
Applying consequences of Einstein´s theory of general relativity to planet hunting certainly has its advantages. In this case, the newly discovered planets would not have likely been discovered. But there are challenges as well. The technique requires highly sensitive measurements and it is not sensitive to small Earth-like worlds.
In the end, this new technique adds to the toolbox astronomers have available to make new discoveries and expand the growing number of planets in our galaxy.
According to a CfA statement, "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."
The researchers' paper has been accepted for publication in The Astrophysical Journal and is available online.
Image 2 (below): This graphic shows Kepler-76b's orbit around a yellow-white, type F star located 2,000 light-years from Earth in the constellation Cygnus. Although Kepler-76b was identified using the BEER effect (see above), it was later found to exhibit a grazing transit, crossing the edge of the star's face as seen from Earth. Credit: Dood Evan