Astronomers catch a planet being born

By Aaron Smith 2 March 2011
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Grainy images of a distant star may help confirm a theory of planet birth more than 300 years old.

A TEAM OF SCIENTISTS from Australia, Spain, France and the US have captured what may be the first images of a Solar System being formed.

The astronomers used powerful new telescopes at the European Southern Observatory’s Paranal Observatory in Chile to look at the disc of debris surrounding the star T Chamaeleontis, 215 lights-years from Earth.

What they found was a ring-shaped space in the disc around the star, suggesting the movement of a nascent planet sweeping up the debris with its gravitational pull. Though these kinds of gaps have been found before, this time they also found an object orbiting within the gap a fiery ball of lava that shows up as a tiny fleck of light.

Holy Grail

“Thousands of astronomers have been chewing their knuckles off for find like this. To get a direct image of a planet forming, even if it is only a speck of light, has been the Holy Grail of astronomy,” says team member Professor Peter Tuthill at the University of Sydney.

“The exciting thing is that this embryonic planet is still inside its own placenta and as it obits around, it sucks up gas and dust,” he told Australian Geographic.

For understanding planetary formation, “this marks a major milestone,” adds lead author Dr Nuria Huélamo of Spain’s Centro de Astrobiologia in Madrid.

Planetary formation theory has suggested that debris leftover from the birth of a star orbits as a flattened disc of dust and gas. This debris then clumps together in a kind of snowball effect until one clump is massive enough that its gravity draws in all of the matter within its vicinity, and a fledgling planet is born.

German philosopher and thinker Immanuel Kant first suggested in the 1700s that this process would result in a gap or ring in the disc surrounding a star, but until now this idea has never been proven, says Peter. “Kant knew the planets orbit all on a common single plane, rather than just at random and from this he extrapolated how planets may have formed: by growing from a spinning pancake of dust and gases.”

Brown dwarf

“Further observations will be needed to confirm that this is, indeed, a young planet,” says Professor Fred Watson of the Australian Astronomical Observatory (AAO) in Siding Spring, NSW.

One question remaining to be resolved is whether the discovery is actually a failed ‘brown dwarf’ star or a young planet, he says. “Although the jury is still out on exactly what we have found here, statistical evidence suggests brown dwarfs are rare…If it is a planet, it will most likely become a gaseous giant like Jupiter or something larger, but I guess we will just have to wait a couple billion years and see what happens.”

“It’s only within the last 16 years that we’ve had the capability of detecting any planets around other stars, let alone seeing them under construction,” Fred adds. “Now, however, for the first time, we have a very sophisticated instrument [in the Paranal Observatory] that can reveal the presence of newly forged young planets embedded in their dusty birthplaces the discs of raw material around their parent stars.”

The research is published in the April edition of the journal Astronomy and Astrophysics.