New Jupiter-size Planet with a Circular Orbit

New Jupiter-size Planet with a Circular Orbit

The star Tau 1 Gruis
Credit: (Digitized Sky Survey image)

An international planet search team on Tuesday announced the discovery of the 102nd planet outside our solar system — a Jupiter-like giant circling a star about 100 light-years away.

The discovery was made by the Anglo-Australian Planet Search Team, in part sponsored by the National Science Foundation. The new planet has a mass of about 1.2 Jupiters and orbits the star Tau 1 Gruis, found in the southern constellation Grus (the crane). It is located about the same distance from its star as our asteroid belt is from our Sun (2.5 astronomical units with 1 AU being the Earth-Sun distance). Its orbit is roughly circular.

Based on a 15-year survey headed by Paul Butler of Carnegie and Geoff Marcy of U.C. Berkeley, about 12 percent of the Sun-like stars in our galaxy have planets that can be detected orbiting their stars within about 5 AU. As the body of extrasolar planets grows, more planets are being found farther out. This finding supports the idea that giant planets in solar systems may form at great distances from their stars and later move inward, according to a news release from the Carnegie Institution in Washington.

As the number of known extrasolar planets continues to grow, astronomers are beginning to see patterns in their characteristics.

"When we first started out, we found planets close in to their parent stars," team member Chris McCarthy of the Carnegie Institution of Washington said in the release. "But as the planet search program has matured, we’re finding more planets farther out and in nearly circular orbits. This means that we are getting closer to detecting more systems that are similar to our own solar system."

Dr. Hugh Jones, of Liverpool John Moores University in the U.K., was the lead astronomer for search project, which was supported by the U.K., Australia, and the United States.

Related Web Sites:

Anglo-Australian Telescope

California & Carnegie Planet Search