Gas-giant exoplanets seen clinging close to their parent stars

HONOLULU, June 27 (UPI) -- U.S. astronomers say they've found distant gas-giant planets are rare around many types of stars and prefer to cling close to their parent stars.

Astronomers at the Gemini Observatory and the University of Hawaii's Institute of Astronomy say the finding could have a significant impact on theories of planetary formation.

Gemini Observatory's recently completed Planet-Finding Campaign found the vast outlying orbital space around many types of stars is largely devoid of gas-giant planets, which apparently tend to dwell close to their parent stars, a university release said Thursday.

"It seems that gas-giant exoplanets are like clinging offspring," Michael Liu, UH astronomer and leader of the Planet-Finding Campaign said.

"Most tend to shun orbital zones far from their parents," he said. "In our search, we could have found gas giants beyond orbital distances corresponding to Uranus and Neptune in our own Solar System, but we didn't find any."

The Gemini Observatory is an international collaboration with two identical 8-meter telescopes, one in Hawaii and one in Chile.

The results from the Gemini South telescope in Chile will help scientists better understand how gas-giant planets form, as the orbital distances of planets are a key signature that astronomers use to test exoplanet formation theories, Liu said.

The findings are mirrored in our own solar system, the researchers said.

"The two largest planets in our Solar System, Jupiter and Saturn, are huddled close to our Sun, within 10 times the distance between the Earth and sun," Eric Nielsen of the University of Hawaii points out. "We found that this lack of gas-giant planets in more distant orbits is typical for nearby stars over a wide range of masses."