Astronomers at the Harvard-Smithsonian Center for Astrophysics have discovered two worlds in an aged solar system that are about to become a snack of cosmic proportions. Their star is a planet-eater.
The planets, Kepler-56b and Kepler-56c, will be swallowed by their star in 130 million and 155 million years, respectively — a short amount of time by astronomical standards. "As far as we know, this is the first time two known exoplanets in a single system have a predicted 'time of death,'" says astronomer Gongjie Li
The star Kepler-56, which is 3,000 light years away from Earth, is becoming a red giant and has already ballooned out to four times the size of our sun. As it continues to age, it will grow larger and its tides will get stronger, dragging its planets inward to their eventual demise. (Our sun will likewise become a red giant in about five billion years, expanding to engulf Mercury and Venus.)
As Kepler-56b and Kepler-56c move closer to the steadily growing star, the intense heat will boil away their atmospheres and the stellar tides will stretch them to the point that they become egg-shaped. The only survivor in the system will be Kepler-56d, a gas giant planet orbiting at a safe distance more than 10 times farther out than its doomed siblings.