Kepler Team Confirms Two Saturn-sized Planets Around a Single Star

Using data from the Kepler spacecraft, scientists have confirmed the discovery of a multi-planet system in the constellation Lyra about 2,000 light years away, made up of at least two gas-giants similar to Saturn in size and mass. The results, which increase the mission’s confirmed planet count to seven since its launch in March 2009, were announced by the Kepler team in a teleconference held today.

William Borucki, Kepler Mission Science Principal Investigator, explained that “instead of taking pictures, [Kepler] measures the brightness of stars,” variations of which are used by scientists to determine characteristics such as the orbital period, mass, and size of the planets that cross or transit them. Matthew Holman, Associate Director of the Theoretical Astrophysics Division at the Harvard-Smithsonian Center for Astrophysics, said that using a technique called “transit timing variations” the team was able to utilize data collected over several months to study successive transits of the planets – Kepler 9B and Kepler 9C – and to analyze the gravitational interaction between them. By studying how the gravity of a planet affects the orbits of others, this technique, which Holman and a group of scientists first proposed in 2005, has now been proven to work as a tool to confirm the presence of planets.

But transit timing variation, which Borucki described as a “new, impressive,” and “important” technique, does much more than just find them. Alycia Weinberger of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington explained that studying the way planets “tug at each other,” which causes those transit variations, can even help teach us about how planets form and how they “migrate” into their particular configuration, a study which may provide clues as to the likelihood of low-mass, Earth-sized planets in other systems. “How a planetary system looks today has a lot to tell us about how it formed,” she added.

The “super-Earth” category planet apparently orbiting the same star may have already been found in this same system, but work is ongoing to confirm this. With an orbital period of 1.6 days, this object would be the smallest planet to be observed in transit. As they keep hard at work to rule out “astrophysical false positives” regarding this third object, the team remains hopeful that this is just the beginning for a mission they expect will yield new exciting discoveries in the years to come.