First planet photographed outside solar system

BBC - 4/30/2005

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Scientists say they have photographed a planet outside the Solar System for the first time. The European Southern Observatory group said the red image is the first direct shot of a planet around another star.

The planet (left) is about five times the size of our Jupiter

 

Artist's rendition of the extrasolar planet (on the left) 

Scientists say they have photographed a planet outside the Solar System for the first time.

The European Southern Observatory group said the red image is the first direct shot of a planet around another star.

The planet, known as 2M1207B, is about five times the size of Jupiter and is orbiting at a distance nearly twice as far as Neptune is from our Sun.

The parent star and planet are more than 200 light-years away near the southern constellation of Hydra.

There has been a lot of competition among astronomers to secure the first direct picture of an exoplanet.

When the ESO group first released the picture last September there was doubt over whether the star and planet were gravitationally bound.

But follow-up images taken at the Very Large Telescope facility in Chile show the two objects are moving together.

"Our new images are quite convincing" said Gael Chauvin, an Eso astronomer.

"This really is a planet - the first planet that has ever been imaged outside of our Solar System" he added.

Tough task

It is extremely difficult for current technology to detect exoplanets - let alone getting a clear shot of one.

All of the 130 or so exoplanets so far discovered have been found using indirect methods - looking for changes in the properties of stars (their brightness or way they move) that can be explained only by the presence of a planet.

Now we have a direct observation, the European and American team says.

The star has the uninspiring catalogue number 2M1207A. It is a brown dwarf, or "failed star" - an object whose mass of hydrogen and helium has failed to trigger the nuclear reactions that would make it shine brightly like normal stars.

At the time of 2M1207B's discovery, it was impossible to prove that the red speck caught in the original images was not a background object, such as an unusual galaxy or a peculiar cool star.

The new observations show with high confidence that the two objects are moving together and hence are gravitationally bound.

"The two objects - the giant planet and the young brown dwarf - are moving together; we have observed them for a year, and the new images essentially confirm our 2004 finding" said Benjamin Zuckerman, a University of California-Los Angeles (UCLA) professor of physics and astronomy.

Anne-Marie Lagrange, another member of the team from the Grenoble Observatory in France, looks towards the future: "Our discovery represents a first step towards one of the most important holy grails of modern astrophysics: to characterise the physical structure and chemical composition of giant and, eventually, terrestrial-like planets"

Dr Chauvin added: "Given the rather unusual properties of the 2M1207 system, the giant planet most probably did not form like the planets in our Solar System"

"Instead it must have formed the same way our Sun formed, by gravitational collapse of a cloud of gas and dust"

As a consequence, there are bound to be some scientists who will still question if 2M1207B really is a planet.

Lynne Hillenbrand, an assistant professor of astronomy at the California Institute of Technology, told the Associated Press news agency: "The claim of an object being a planet is subject to one's definition of planet, and there are different camps on what that definition is"

What everybody wants is a direct image of a rocky planet like Earth circling another star. But this will not come until we get the next generation of super-telescopes capable of resolving such small, faint objects.

The latest research has been accepted in Astronomy and Astrophysics, a premier journal in astronomy.