Mauna Kea team finds
two new planets

Two Jupiter-size planets are
discovered orbiting around
distant stars

By Rod Ohira
Star-Bulletin

Planet hunters from the top of Mauna Kea have made two more discoveries in their probe of the unknown horizon which could reveal secrets of the universe.

With assistance from a 25-year-old college student in England, a four-member team of San Francisco State researchers yesterday announced the discovery of two Jupiter-size planets orbiting around distant stars.

The findings bring to 12 the number of planets discovered beyond the solar system, including nine by the team of Geoffrey Marcy, Paul Butler, Steve Vogt and Debra Fischer.

One of the newly discovered planets orbits star HD210277 and has a year that is about 437 days long, say researchers.

The star is slightly bigger than the sun and is 68 light-years away, in the direction of the constellation Aquarius.

The distance between the planet and its star is about the same as the Earth and sun, which is significant since it's the first planet outside the solar system discovered at such a familiar distance, they added.

"We had discovered planets that orbit much closer and much farther from their stars than the Earth-sun distance," Marcy said in a written statement.

"We wondered if nature rarely puts planets at one Earth-sun distance. Now we know that such planets are not rare."

One of the team's goals is to find Jupiter-size planets farther from their stars. Five Earth-sun distances, for example, would be a signpost for solar systems like ours, Marcy said.

After putting together a target list of 430 candidate stars, the discovery team launched a planet search covering 12 nights of observations from W.M. Keck Observatory at Mauna Kea over a nine-month period.

The two new discoveries were found off the candidate list.

The second new planet orbits star HD187123 every three days.

The star is 154 light-years away in the constellation Cygnus (the Swan) and has the same size, mass, temperature and luminosity as the sun but is richer in heavy elements such as iron, the scientists said.

It was discovered with the help of a list compiled by Kevin Apps, a student at the University of Sussex in England.

Apps, majoring in physics and astrophysics, contacted Marcy and Butler last year and asked to see the target list for their planet search.

After analyzing the target stars' temperature, luminosity, composition and other features using new satellite data available on the Internet, Apps found 30 stars on the list that were not good candidates.

Apps offered the astronomers a list of 30 "solar ringers," which Marcy and Butler accepted.

The two planets were discovered by detecting a characteristic wobble in the motion of the star caused by the gravitational effect of the planet orbiting the star, researchers said.

"The search for planets is the hottest frontier," Keck Observatory spokesman Andrew Perala said. "Right now, all theories have been chucked out the window.

"In 1996, 10 percent of the stars were thought to have planets. We now think 50 percent of them have planets. And there are 100 billion stars in the galaxy."

The technical paper and graphs on the discovery of HD187123 can be viewed at http://cannon.sfsu. edu/~gmarcy/planetsearch/papers.html.