Tel Aviv U. helps discover new planet
Scientists use Einstein's theory of general relativity to detect 'beaming' effect in stars -- telltale signs of an orbiting body
A team of astronomers at Tel Aviv University and the Harvard-Smithsonian Center for Astrophysics announced the first-ever discovery of an extrasolar planet using new detection methods developed by the Israeli institution.
Professor Tsevi Mazeh and his PhD student, Simchon Faigler, from the School of Physics and Astronomy at TAU, noticed brightness variations in a star located in the constellation Cygnus, 2,000 light years away from earth, which led them to determine the existence of an orbiting planet, with twice the mass of Jupiter, which they dubbed Kepler-76b.
Mazeh’s technique is based on identifying three very small effects that occur simultaneously as a planet orbits a star. The first effect is Einstein’s relativistic “beaming” effect that causes a star to brighten and dim as it is tugged back and forth by an orbiting planet.
The second effect that the Faigler-Mazeh method looks for is the stretching of a star into a football shape by the gravitational tides raised by an orbiting planet. A star distorted this way appears brighter when observed from the side, due to the larger visible surface area, and fainter when viewed end-on. The third small effect is due to starlight reflected by the planet itself.
Because the brightness variations are extremely small (on the order of one part in ten-thousand), these effects can be detected only with accurate data obtained by space missions. The Tel Aviv team analyzed data for more than one hundred thousand stars obtained with the NASA space mission Kepler, looking for the beaming and the two other modulations. After discovering a planet candidate, they collaborate with Dr. David Latham from the Center for Astrophysics and his team, which includes Dr. Lars Buchhave, to observe the candidate from the ground for additional spectroscopic confirmation.
Faigler and Mazeh noticed the three effects in one of the stars observed by Kepler. Ground-based observations to confirm the planet detection were performed by Latham and his team at the Whipple Observatory in Arizona, and by Lev Tal-Or, another PhD student from Tel Aviv, at the Haute-Provence Observatory in France. Both telescopes confirmed unequivocally the existence of the planet, now called Kepler-76b.
“This is the first time that this aspect of Einstein’s Theory of Relativity has been used to discover a planet,” said Mazeh. “We have been searching for this elusive effect for more than two years, and we finally found a planet… It is a dream come true.”
“The discovery proves the feasibility of the method,” says Faigler. “We hope to find more planets like Kepler-76b using the same technique. This is possible only because of the exquisite data NASA is collecting with the Kepler spacecraft for more than 150,000 stars.”