Exoplanets Galore

Exoplanets are enjoying the spotlight at the American Astronomical Society meeting in Boston this week. The Kepler mission is reporting many new findings—smaller planets, multiple planet systems and a scorched, rocky planet.

Smaller Planets

Local scientists from NASA Ames and UC Berkeley have determined that smaller planets rule the galaxy. From Scientific American:

“There are some Jupiters, there are some Saturns," University of California, Berkeley, astronomer Geoff Marcy said… "But there are far more of the smaller and smaller planets going down to about two Earth diameters.”

Planets our size, says Marcy, will take more time to identify.

Multiples

Surprisingly, one third of the planetary systems that Kepler has found host multiple planets—from two to six planets.

“We didn't anticipate that we would find so many multiple-transit systems. We thought we might see two or three. Instead, we found more than 100,” said Smithsonian astronomer David Latham.

These systems are quite different from our solar system—they’re much flatter. They have to be for Kepler to spot them. Kepler watches for a planet to cross in front of its star, blocking a tiny fraction of the star's light. By measuring how much the star dims during such a transit, astronomers can calculate the planet's size, and by observing the time between successive events they can derive the orbital period - how long it takes the planet to revolve around its star.

Kepler 10c

Earlier this year, the Kepler team announced the findings of Kepler 10b. This week, its sibling, 10c, was introduced. Like 10b, Kepler 10c is a scorched, hot, rocky planet, larger than Earth, about 2.2 times the size. It’s the confirmation of Kepler 10c that’s causing some stir. Universe Today explains why:

Kepler-10c was validated using a new computer simulation technique called “Blender” as well as additional infrared data from NASA’s Spitzer Space Telescope. This method can be used to locate Earth-sized planets within Kepler’s field of view and could also potentially help find Earth-sized planets within other stars’ habitable zones.

This is the first time the team feels sure that it has exhaustively ruled out alternative explanations for dips in the brightness of a star… basically, they are 99.998% sure that Kepler-10c exists.

Image credit: NASA/Ames/JPL-Caltech