First-ever photo of planet outside our Solar System?

Posted Sept. 10, 2004
European Southern Observatory and
World Science Staff

The European Southern Observatory released this composite image of the brown dwarf designated 2M1207 (center) and the fainter object seen near it, designated "Giant Planet Candidate Companion." It may the first image of an exoplanet, or a planet outsider our own solar system. It was imaged with the Yepun telescope at the ESO Paranal Observatory in Chile.

Astronomers say they may have taken the first photo ever made of a planet orbiting a star other than our Sun.

"It may indeed be the first planetary system beyond our own ever imaged," said Christophe Dumas of the European Southern Observatory, a member of the team of astronomers who took the snapshot.

Further tests are needed to find out whether it's really a planet. Several times in past years, similar photos of faint objects raised hopes that the objects were planets, but they didn't turn out to be.

This one may be different, the astronomers insist.

This planet, if it is one, shows signs of having water, the astronomers said. Unfortunately, it may be very unlikely to have life, partly because it is much too huge.

The journey toward finding the object began last April, when the astronomers detected a faint, red point of light about 230 light-years away, using the Paranal Observatory in Chile. The red point was very near a type of "failed star" known as a brown dwarf, a star-like object that is very dim because it is too small to become a true star.

Analysis of the light from the red point pointed to chemical signatures of water molecules and other characteristics considered consistent with the signs of a recently formed, hot, and very big planet, the researchers said. But it could also turn out to be another brown dwarf, they added.

For now, they're calling it a "Giant Planet Candidate Companion." Their findings about it will appear in the research journal Astronomy and Astrophysics, they said. Next, they plan to analyze whether the object's motion is consistent with that of a planet, which should take a year or two.

Just a speck of light

Since 1998, European and American astronomers have been studying nearby "stellar associations," large bunches of mostly young stars. Surrounding these stars are dust and gas clouds, the material from which the stars formed.

These stars are considered good places to look for possible planets or similar objects. That's because they're "much hotter and brighter when young," and thus easier to find with telescopes, said the European Southern Observatory Gael's Gael Chauvin, another member of the research team.

The team focused on one such group of stars, in the direction of the constellation Hydra deep down in southern sky. They used a giant telescope designed to cancel out image distortions caused by air movements our atmosphere. Without that feature, the faint red object "would not have been seen," said Chauvin.

"The thrill of seeing this faint source of light in real-time on the instrument display was unbelievable," he said.

But the new planet, if it is one, is much different from Earth. It has characteristics that most astronomers say would make it very hard for such a planet to harbor life.

For one, it's much bigger than Earth, the researchers said. It also orbits its parent brown dwarf at a distance more than 50 times greater than the distance at which the Earth lies from the Sun. Also, analysis of its light showed that it's about five times heavier than our Solar System's biggest planet, Jupiter.

Because our solar system is 4,600 million years old, there is no way to directly measure how the Earth and other planets formed. But if astronomers can study the vicinity of young stars, then by witnessing planetary systems now forming, they will be able to better understand our own distant origins.

Anne-Marie Lagrange, another member of the research team from Grenoble Observatory, said "our discovery represents a first step towards opening a whole new field in astrophysics: the imaging and spectroscopic study of planetary systems." Spectroscopic study is the analysis of light waves from distant objects in order to determine their character.

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