COURTESY OF THE GEMINI OBSERVATORY This Jon Lomberg painting shows the relative size of a typical brown dwarf compared to the sun, a small star, and two planets.

UH photo may be
first to show a planet
outside solar system

A separate discovery reveals a
brown dwarf where none should be

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By Rod Thompson
rthompson@starbulletin.com

WAIKOLOA, Hawaii >> University of Hawaii astronomers have taken pictures of what may be the first planet ever seen outside the solar system.

University astronomer Eduardo Martin says his team will not know for at least two years if they have taken pictures of a large, young planet or an old, brown dwarf, a class of objects sometimes called "failed stars."

Meanwhile, Gemini North Observatory announced that astronomers using its telescope have seen an object that is definitely a brown dwarf, but one that is much closer to its main star than previously thought possible.

Both announcements were made as part of the International Astronomical Union's Symposium on Brown Dwarfs at the Outrigger Waikoloa Beach hotel this week.

Stars produce heat by nuclear reactions, while brown dwarfs produce heat by gravity compressing gas.

A lively debate is under way at the symposium on what should be called a brown dwarf and what should be considered a large planet like Jupiter, Martin said.

In 1998 on the Keck I telescope, Martin and colleague Victor Bejar first saw what could be a dwarf or a planet near a star called Sigma Orionis in the belt of the constellation Orion.

Although the presence of planets outside the solar system has been inferred from the wobble of stars, no picture had ever been taken of one until, possibly, the Sigma Orionis object, Martin said.

Martin and Bejar did additional studies on the William Herschel Telescope in the Canary Islands in 2000, but more studies on the Hubble Space Telescope are needed to decide whether the object is a planet, Martin said.

While the Sigma Orionis object is just three times the mass of Jupiter, University of Arizona astronomer Laird Close used the Gemini North telescope to study a dwarf near the celestial equator that is as much as 70 times the mass of Jupiter.

The surprise was that the heavy dwarf is orbiting a small, "low-mass" star at a distance just three times the distance of the earth from the sun, 93 million miles. Using the earth-sun yardstick, astronomers have found dwarfs typically cluster at 30 times the distance.

The area close to a star was supposed to be a "brown dwarf desert," but Laird's discovery means that concept will have to be changed.

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University of Hawaii

UH Institute for Astronomy