Second smallest exoplanet found to date is only 4 times Earth's mass

Washington, January 8 (ANI): A team of astronomers, using the Keck Observatory, has discovered the second smallest exoplanet, which is only four times the mass of Earth.

Dubbed HD156668b, the planet orbits its parent star in just over four days and is located roughly 80 light years from Earth in the direction of the constellation Hercules.

"This is quite a remarkable discovery," said astronomer Andrew Howard of the University of California at Berkeley, or UCB. "It shows that we can push down and find smaller and smaller planets," he added.

Howard, along with his colleagues from the California Planet Search team (CPS) Geoff Marcy of UCB, Debra Fischer of Yale University, John Johnson of the California of Institute of Technology and Jason Wright of Penn State University, discovered the new planet with the 10-meter Keck I telescope atop Mauna Kea in Hawaii.

The researchers used the radial velocity or wobble method, which relies on Keck's High Resolution Echelle Spectrograph, or HIRES instrument, to spread light collected from the telescope into its component wavelengths or colors, in order to find the planet.

Nearly 400 planets around other stars were discovered using this technique.

But, the majority of these planets are Jupiter-sized or larger.

"It's been astronomers long-standing goal to find low mass planets, but they are really hard to detect," Howard said.

He added that the new discovery has implications for not only exoplanet research, but also for solving the puzzle of how planets and planetary systems form and evolve.

Astronomers have pieces of the formation and evolutionary puzzle from the discovery of hundreds of high-mass planets.

But, "there are important pieces, we don't have yet. We need to understand how low mass planets, like super-Earths, form and migrate," Howard said. (ANI)