Kepler's Transit Trio
The measurements were made using NASA’s Kepler spacecraft and were confirmed by the W. M. Keck Observatory in Hawaii. The observations are published in the journal Science.
“This system of planets is a thrilling example of the Kepler mission’s power,” said co-author Tim Brown, scientific director of the Las Cumbres Observatory Global Network.
“It is astounding that Kepler can show us, circling one star, a pair of planets that pull each other’s orbits around, and also an object that is likely a planet not much bigger than the Earth,” he said. “Rich systems like this one will be the best laboratories for understanding how planets form, and how planetary systems evolve.”
The Kepler mission looks for the data signatures of planets by measuring tiny decreases in the brightness of stars when planets transit or cross in front of them. In June of this year, mission scientists announced that the mission has identified more than 700 planet candidates, including five candidate systems that appear to have more than one transiting planet.
The data suggest the transits of a super-Earth-sized planet about 1.5 times the radius of Earth in a scorching, near-Sun 1.6 day-orbit. Additional observations are required to determine whether this signal is indeed a planet or an astronomical phenomenon that mimics the appearance of a transit.
Launched in 2009, the Kepler space-borne telescope is designed to search the nearby region of our galaxy for planets the size of Earth, orbiting in the habitable zone of stars similar to our Sun. Scientists describe the habitable zone as the region around a star where temperatures permit water to be liquid on a planet’s surface.
Liquid water is considered essential for the existence of life as we know it. Therefore, the challenge for Kepler is to look at a large number of stars in order to statistically estimate the total number of Earth-size planets orbiting Sun-like stars in the habitable zone. Kepler will survey more than 100,000 stars in our galaxy.