The discovery of two exoplanet "companions" provides insight into how planets are formed.

The hot Jupiter solar system, discovered from data collected by the K2 mission, contains two close-in planetary companions, the University of Michigan reported. Out of the some 300 hot Jupiters that have been spotted over the past two decades, these new objects are the first close-in planets to be discovered.

"This is really exciting," said Juliette Becker, a graduate student at U-M's Astronomy Department in the College of Literature, Science, and the Arts, and the lead author of a paper highlighting the discovery. "People have looked for these planets and have looked in data that exists for hot Jupiters for years and nothing has come up. So people took it to mean that it was not possible to have these close-in planet companions."

Hot Jupiters are large and gaseous and situated extremely close to their host stars. These planets are believed to form in freezing temperatures, which contradicts their position close to a scorching Sun. The phenomenon has left scientists wondering how hot Jupiters get to their locations roughly 10 to 20 times the radius of the sun away from their stars.

"The whole theory of planet formation and migration is not totally understood," Becker said. "Even today there is a lot of active work being done to figure out how Jupiter got where it was. So anything we can discover on how hot Jupiters migrate is useful in understanding planet formation and migration as a whole."

This new insight from the Kepler space telescope could bring us closer to solving the mystery.

The findings were published in a recent edition of the Astrophysical Journal Letters.